Warships in the United States Navy were first designated and numbered in a system originating in 1895. Under this system, ships were designated as "Battleship X", "Cruiser X", "Destroyer X", "Torpedo Boat X" and so forth where X was the series hull number as authorized by the US Congress. These designations were usually abbreviated as "B-X", "C-X", "D-X", "TB-X," etc. This system became cumbersome by 1920, as many new ship types had been developed during World War I that needed new categories assigned, especially in the Auxiliary ship area.

To rectify this problem, on 17 July 1920, Acting Secretary of the Navy Robert E. Coontz issued General Order No. 521, "Standard Nomenclature for Naval Vessels." This document created a standardized system of alpha-numeric symbols to identify ship types such that all ships were now designated with a two letter code and a hull number, with the first letter being the ship type and the second letter being the sub-type. For example, the destroyer tender USS Melville, first commissioned as "Destroyer Tender No. 2" in 1915, was now re-designated as "AD-2" with the "A" standing for Auxiliary, the "D" for Destroyer (Tender) and the "2" meaning the second ship in that series. Ship types that did not have a sub-classification simply repeated the first letter. This meant that Battleships became "BB-X" and Destroyers became "DD-X" with X being the same number as previously assigned. Ships that changed classifications were given new hull numbers within their new designation series.

The Navy has updated these designations many times over the past century with the most recent (as of 2019) being "Classification of Naval Ships and Craft, SECNAVINST 5030.8C" which was issued in 2016. See below for copies of both the 1920 and the 2016 documents.

The designation "USS" standing for "United States Ship" was adopted in 1909. Prior to that time, no designation was used in official documents. New-construction ships not yet in commission do not use "USS" and are instead prefixed with "PCU" which stands for "Pre-Commissioning Unit." Ships that are out of commission also do not use "USS" and are properly referenced only by their names.

It should be noted that in the United States Navy, unlike European Navies, the first ship in a class to be authorized by the US Congress is the designated class leader (class name ship), regardless of the order in which the ships of that class are laid down, launched or commissioned. For example, contrary to many European texts, for the last class of "Standard" battleships, the battleship USS Colorado BB-45 (commissioned 30 August 1923) is the class leader under USN designation standards, not USS Maryland BB-46 (commissioned 21 July 1921). These battleships are thus properly designated as being "USS Colorado BB-45 Class" and not as "USS Maryland BB-46 Class."

Please note that the listings below include many designations that are no longer in use by the current-day US Navy and that others were proposed designations not actually used or were intended for ships that were never built. Red italicized designations are for those ships actually in commission or currently under construction as of the present time (2019).

The ex-collier USS Langley AC-3 was rebuilt and recommissioned as the first US aircraft carrier CV-1 on 20 March 1922. The CVB designation was approved by the Secretary of the Navy on 10 June 1943 and the CVL designation was approved on 15 July 1943. The CVS designation was established in 1953 with USS Bunker Hill (CVS-17) being the first so designated on 8 August 1953, although she was in reserve at the time and never did recommission. The designation CVA replaced both CV and CVB on 1 October 1952. CVL went out of use on 15 May 1959 when the last light carrier was decommissioned. With the decommissioning of the last CVS in 1974, CV and CVN replaced CVA and CVAN on 30 June 1975 as carriers were now considered to be multi-mission capable rather than specialized. The CV (non-nuclear) designation went out of service when the last conventionally powered carrier, USS Kitty Hawk CV-63, was decommissioned on 12 May 2009.

Escort Aircraft Carriers were originally designated AVG (Escort Carrier, Auxiliary) on 31 March 1941, with the USS Long Island AVG-1 being the first ship so commissioned on 2 June 1941. This designation was changed on 20 August 1942 to ACV (Aircraft Carrier, Auxiliary), and then changed again on 15 July 1943 to CVE. Escort Carriers built for the British Royal Navy were designated BAVG until they were transferred. The CVE designation went out of use when the remaining escort carriers were reclassified AKV (Auxiliary, Aircraft Ferry) on 7 May 1959.

A common question is "what does the 'V' stand for in CV or CVA or CVS or CVE?"

[Thanks to C. Bossie who provided much of the following answer.]

The following is taken from "United States Naval Aviation 1910-1995, Appendix 16: US Navy and Marine Corps Squadron Designations and Abbreviations":

On 17 July 1920, the Secretary of the Navy prescribed a standard nomenclature for types and classes of NAVAL VESSELs, including aircraft, in which lighter-than air craft were identified by the type "Z" and heavier-than air craft by the letter "V". The reference also speculates that: "The use of the "V" designation has been a question since the 1920s. However, no conclusive evidence has been found to identify why the letter "V" was chosen. It is generally believed the "V" was in reference to the French word volplane. As a verb, the word means to glide or soar. As a noun, it described an aeronautical device sustained in the air by lifting devices (wings), as opposed to the bag of gas that the airships (denoted by "Z") used. The same case may be regarding the use of "Z". It is generally believed the "Z" was used in deference to Count Ferdinand von Zeppelin. However, documentation has not been located to verify this assumption."

In European NATO Countries, "R" is used to designate an aircraft carrier.

The early pre-dreadnoughts Maine and Texas were commissioned as "Second Class Battleships" but apparently did not receive hull series numbers. Maine was originally designated as Armored Cruiser #1 (ACR-1) but was reclassified during construction.

Many pre-dreadnoughts were colloquially known as "Coastal Defense Ships" as they were not designed nor intended to fight far from home. Some of these were officially renamed as "Coast Battleship #X" (with "X" being their hull number) in March - April 1919 in order to free up their names for new construction. Surviving pre-dreadnoughts were reclassified as "Battleships" and given the BB designation in the 17 July 1920 assignment, although many of these were then rapidly scrapped under the terms of the Washington Naval Limitation Treaty.

The "BBC" "BBG" and "BBH" designations were all for proposed conversions of Iowa class (BB-61) battleships. The first two were developed during the 1950s while the last one was planned during the 1980s commissions. None of these conversions ever took place.

Monitors were coastal defense ships of the 1890s, obsolete even as commissioned.

The history of cruiser classification is somewhat complicated. Prior to 1920, there were three major classifications:

• The categories of Protected Cruisers, Peace Cruisers, Third Class Cruisers and Unprotected Cruisers were all designated "C-X"
• Armored Cruisers were designated "ACR-X"
• Scout Cruisers were designated "CS-X"

where "X" was the hull series number.

There were also older and non-classified cruisers which had not been assigned classifications or hull numbers.

The United States built her first torpedo boat Cushing (TB-1) in 1890 and her last Wilkes (TB-35) in 1902. Most of these were decommissioned or re-purposed prior to the start of World War I. The surviving Torpedo Boats were renamed on 01 August 1918 as "Coast Torpedo Boat #X" where "X" was a new numeric series, starting with # 1. This number was given to the former USS Foote (TB-3) which was now renamed as USS Coast Torpedo Boat # 1 (TB-3). Like the old pre-dreadnought battleships mentioned above, this renaming of torpedo boats was done in order to free up their names for new destroyers. All of these torpedo boats were decommissioned the following year and soon afterwards sold for scrap. As these boats were all gone prior to the 17 July 1920 redesignation, the Torpedo Boat designation went out of service and was not replaced with a new one. New small warships of about this size were now designated in the Patrol Vessel category.

The first USN destroyer was Bainbridge (D-1) which completed in 1902. The designation for all existing destroyers was changed from "D-X" to "DD-X" as part of the 20 July 1921 redesignation mentioned above. During prohibition, twenty-five destroyers were loaned to the US Coast Guard and these ships were redesignated as "CG-X" starting with USS Cassin (DD-43) which became CG-1 on 7 June 1924. Most of these destroyers were scrapped following their return to the USN after the end of prohibition but a few were retained and these few were given back their previous DD designation and hull number.

Following World War II, many Fletcher (DD-445), Allen M. Sumner (DD-692) and Gearing (DD-710) class destroyers were modified and given new, specialized missions as Fleet Escorts (DDE), Radar Pickets (DDR) and ASW submarine killers (DDK). The ASW destroyers (DDK) were redesignated as Fleet Escort destroyers (DDE) on 4 March 1950. All Fleet Escort destroyers (DDE) were reclassified as destroyers (DD) on 30 June 1962. Most radar picket destroyers (DDR) were reclassified as destroyers (DD) during the 1960s. One Fleet Escort destroyer USS Saufley (DDE-465) was reclassified as an Experimental Escort Destroyer (EDDE) on 1 January 1951 and then used as a test bed during the 1950s for sonar and ASW experiments. She was reclassified as a general purpose destroyer (DD-465) on 1 July 1962.

Faced with a growing Soviet submarine threat, several conversions of the Benson/Livermore (DD-421/DD-429) classes to an ASW "corvette" (DDC) design were proposed for FY1955. This would have entailed removing one boiler and a five-inch gun so as to increase tankerage and ASW capabilities. Nothing came of these proposals and most of these ships remained decommissioned until they were scrapped in the late 1960s and early 1970s.

USS Gyatt (DD-712) was modified to carry a twin Terrier launcher and she was designated as DDG-712 on 1 December 1956. She was redesignated as DDG-1 on 23 May 1957. Her missile emplacement was later removed and her designation reverted back to DD-712 on 1 October 1962.

The "DL" designation meaning "Destroyer Leader" was originally created as part of the 17 July 1920 designation system revision. This designation was not assigned to any ship prior to 2 February 1951 when the ASW cruiser USS Norfolk CLK-1 was redesignated as DL-1 as described above. In addition, the new fleet destroyers of the Mitscher class, which were originally designated in the DD series as DD-927 to DD-930, were redesignated on 2 February 1951 as DL-2 to DL-5. This designation change was meant to indicate that these warships were significantly larger than those destroyers built during World War II yet still smaller than cruisers. As these warships were not really "leaders" in the sense of being equipped as destroyer flotilla leaders, the DL designation was reauthorized to mean "Frigate" on 1 January 1955.

The follow-on Farragut class frigates were originally to be an all-gun design and the first three ships of this class were designated as DL-6 to DL-8. The next three ships starting with USS Coontz were to a similar design but were given a Terrier missile launcher and were designated accordingly as DLG-1 to DLG-3. However, the Navy subsequently decided to equip the Farragut class with Terrier missile launchers and their designation was then changed to become DLG-6 to DLG-8 on 14 November 1956. USS Coontz and her sisters were renumbered in sequence starting with DLG-9 on that same date. As a result of these changes, all DL and DLG warships were in the same hull number series.

The Mitscher class frigates Mitscher (DL-2) and John McCain (DL-3) were converted to carry a Tartar missile launcher during the 1960s and they were then redesignated as missile destroyers DDG-35 and DDG-36, respectively, in 1968-69. As noted above in the cruiser section, on 30 June 1975 most Frigates were redesignated as CG and CGN with the same hull number as used previously, the exception being the Farragut DLG class which were redesignated as missile destroyers DDG-37 through DDG-46.

The designation "DE" was originally assigned to the Destroyer Escorts of World War II. The "DE" designation was changed to mean "Ocean Escorts" for those convoy escorts of the 1950s-1970s starting with the USS Dealey (DE-1006) class and ending with the USS Knox (DE-1052) class, but this was a seldom-used term. The DANFS entry for USS Knox herself describes her as "the prototype in a new class of destroyer escorts" while the Naval Vessel Register (NVR) currently lists all DE-designated ships as simply "Escort" including those built during World War II. As stated above, existing Guided Missile Escorts (DEG) were redesignated as Guided Missile Frigates (FFG) and those Escorts (DE) still in commission were redesignated as Frigates (FF) on 30 June 1975.

Some Edsall (DE-129) class destroyer escorts were converted to Radar Picket (DER) ships during the 1950s. They carried this designation during the rest of their careers, although none of them appear to have been used in that role after about 1960. As part of the 30 June 1975 reclassification program described above, two of these ships, USS Camp (DER-251) and USS Forster (DER-334) were redesignated as Radar Picket Frigates FFR-251 and FFR-334, respectively. These two ships had been transferred to the Republic of Vietnam during the 1970s. When that nation fell at the end of the Vietnam War, Camp escaped to the Philippines but Forester was captured on 30 April 1975 and so was not under USA control at the time of her redesignation two months later.

Three Destroyer Escorts (DE-698, DE-704 and DE-705) were converted to Amphibious Control Ships (DEC) in 1950-51 by adding extra communications gear, but they were all placed back into reserve by 1954 and the designation was abolished in 1957. The amphibious control role was taken over by the APD flagships.

The "PF" designation was originally used for World War II frigates of the Asheville (PF-1) and Tacoma (PF-3) classes. In the 1970s, it was proposed to designate what became the Oliver Hazard Perry (FFG-7) class as PF which would have then meant "Patrol Frigates." In the end, these ships were designated simply as "Frigates."

During the late 1960s and early 1970s, a series of design studies were made for the "next generation" of ASW and guided missile carrier escorts. These warship designs were given various interim designations, such as "DX" for the conventionally powered ASW destroyers, "DXG" for conventionally powered guided missile destroyers, "DXGN" for nuclear powered guided missile destroyers and "DG/Aegis" for an "austere" Aegis missile destroyer. These proposals coalesced around what eventually became the conventionally powered Spruance (DD-963) ASW destroyers and Ticonderoga (CG-47) Aegis missile cruisers. The nuclear powered version, which had grown considerably in size and was now known as a "Strike Cruiser" or CSGN and then later as the "CGN-42" class, was cancelled in the fall of 1978 although it was resurrected a few times until being cancelled once and for all in 1983.

A similar series of interim designations was used for new destroyer and cruiser designs during the early 2000s, respectively "DD-21" and "CG-21" until these temporary ones were replaced with the formal "DD(X)" and "CG(X)" designations. The first destroyer in the DD(X) series was christened as USS Zumwalt (DDG-1000). This meant that these ships are numbered in the DD series, rather than the DDG series, and it appears likely that the unused hull numbers DD-998 and DD-999 will not be assigned to any ship. As of this time (2019), no CG(X) cruisers have been funded or laid down.

As expected, the schedule delays and ballooning costs of the Zumwalt class destroyers has resulted in additional orders for Arleigh Burke DDGs and it is now expected that advanced versions of this class will continue in production for at least the next decade.

The DD designation went out of service when "the last destroyer" USS Cushing DD-985 was decommissioned on 21 September 2005. As noted above, the first US Torpedo Boat (TB-1) was also named Cushing.

In January 2015 the Navy announced that new ships in the Freedom (LCS-1) and Independence (LCS-2) classes would now be designated as Frigates (FF). However, Navy later decided to discontinue building new LCS ships and will dispose of those they do have. As of 2021, no frigates are in commission in the USN, but it is planned to start construction in the summer of 2021 of a new FFG class, the USS Constellation (FFG-62) type.

Early submarines were given the designation "Submarine Torpedo Boats" (later shortened to just "Submarine") and most were given fish names. On 17 November 1911 these names were discontinued and in their place was substituted an alphanumeric designation system representing their class and sequence. For example, USS Bonita (S-15) was renamed as USS C-4 (S-15), with C-4 meaning that she was a member of the third class of USN submarines and the fourth submarine of that class. Newer classes of submarines generally followed the letters of the alphabet, with "S" being the last letter used during the building spree generated by World War I.

Special note should be made here of the only US ship with a "half" hull number, the submarine USS Seal / G-1 which was assigned hull number S-19 ½, apparently because the Navy did not want her and thought that she would not be approved for service. She was eventually redesignated as S-20 sometime prior to her decommissioning on 6 March 1920. This was a reuse of the hull number previously assigned to USS F-1 which had been lost in a collision on 17 December 1917.

Following the reclassification of 1920, all of the older submarines changed their hull series number designation from S to SS, but new submarines built during the mid-1920s to 1931 period were separated into different hull number series, depending upon their assigned role. Fleet Submarines (SF) were intended to scout ahead of the battle fleet, Cruiser Submarines (SC) were larger boats with heavy gun armament while the single Minelayer Submarine (SM) had special tubes for launching mines. All of these newer submarines were given "V" alphanumeric names, although most of them were to differing designs.

This rather confusing practice of giving submarines both an alphanumeric name and an alphanumeric designation was continued until 1931. In that and the following year, all of the submarines built since the mid-1920s were given fish names and redesignated into the SS hull number series. The older submarines built during and immediately after World War I continued with their alphanumeric names (mainly the O, R and S classes). New submarines built since 1931 have continued to be designated into the SS numeric series, with a few exceptions, as detailed below.

In a reprise of the alphanumeric naming of the 1911 to 1931 period, Training and Hunter-Killer submarines of the 1950s originally had only an alpha-numeric designation instead of a hull number. Training submarine SST-1 was commissioned as "T-1" and SST-2 was "T-2." On 15 May 1956 these training submarines were given fish names but they retained their SST designations and hull numbers throughout their service lives. In a similar fashion, the "Hunter-Killer" ASW submarines SSK-1, SSK-2 and SSK-3 of that period were also given only alphanumeric names, "K-X" with the X being the same number as in their hull designations. On 15 December 1955, these three boats were given standard fish names and on 15 August 1959 they were renumbered into the SS series.

The modern Seawolf class submarines were designated as SSN-21 to SSN-23, with this apparently meaning "21st century" submarine. This designation seems to have been an aberration, as the follow-on Virginia class submarines continue the previous series, starting at SSN-774.

Some former Ohio (SSBN-726) class ballistic missile submarines were converted during the early 2000s into Tomahawk-carrying guided missile submarines (SSGN).

Most of the larger "Landing Craft" of World War II were later reclassified as "Landing Ships."

The "PG" designation was given both to patrol gunboats built in the US during the first half of the twentieth century and to corvettes transferred from the Royal Navy under reverse lend-lease in 1942.

Many of the "Monitor," "Patrol Boat" and "Patrol Craft" designations were assigned during the Vietnam War. The end of that war retired these designations.

The "LCS" designation was originally assigned during World War II to "Landing Craft, Support." In 2004, the USN reassigned this designation to the "Littoral Combat Ship" for the Freedom (LCS-1) and Independence (LCS-2) classes. In January 2015 the Navy announced that new ships in these classes would now be designated as Frigates (FF). However, Navy later decided to discontinue building new LCS ships and to replace them with a new FFG design.

As noted above in the Cruiser section, the "CM" designation was originally given to the ex-cruisers USS Baltimore (CM-1) and USS San Francisco (CM-2) which were converted to minelayers but retained in the cruiser category.

Those Benson and Gleaves class destroyers converted to minesweepers (DMS) during World War II were reclassified as destroyers (DD) during 1954/1955.

Starting in 1955 the Navy started using "M" as the first letter in the designations for Minewarfare ships and many ships changed designations as a result. The following types were reclassified on 7 February 1955:

• Minesweepers (AM) were redesignated either as Fleet Minesweepers, Steel Hull (MSF) or as Ocean Minesweepers (MSO).
• Motor Minesweepers (AMS) were redesignated as Coastal Minesweeper, Old (MSCO).
• Auxiliary Minelayers (ACM) were redesignated as Auxiliary Minelayers (MMA).
• Fleet Minelayer USS Terror (CM-5) was redesignated as Fleet Minelayer (MM-5). Her designation was changed again to Fleet Minelayer (MMF-5) in October 1955.
• The USS Robert H. Smith (DM-23) class Light Minelayers (converted Allen M. Sumner class destroyers) were redesignated as Destroyer Minelayers (DM). These ships were later redesignated as Fast Minelayers (MMD) on 1 January 1969.

Attack Cargo (AKA) and Attack Personnel Transport (APA) ships differ from Cargo (AK) and Personnel Transport (AP) ships by being specially equipped to partake in amphibious landings. The AKA and APA designations were replaced by LKA and LPA as of 1 January 1969.

Despite having been captured in 1968, USS Pueblo (AGER-2) officially remains in commission as of this date (2019).

AFSB, JHSV and MLP were reclassified as ESB, EPF and ESD, respectively, in September 2015. These ships are now listed below in the Expeditionary Forces section.

The EPF, ESD and ESB ships were originally called the Joint High Speed Vessel (JHSV), Mobile Landing Platform (MLP) and the MLP Afloat Forward Staging Base (AFSB), respectively. In September 2015, the Secretary of the Navy re-designated these hulls to conform to traditional three-letter ship designations.

These ships are part of the Military Sealift Command and are therefore designated as USNS rather than USS for that reason. Military Sealift Command vessels usually have civilian crews.

The two hundred year-old USS Constitution is unique in that she is the only commissioned ship in the USN that does not have a classification other than her name. The Secretary of the Navy, J. William Middendorf, II, ordered her reclassification from "IX-21" to "None" effective as of 1 September 1975. She is now listed on the Naval Vessel Register (NVR) of active in-commission ships only by her name.

These links are to OFF-SITE webpages belonging to the U.S. Navy.

U.S. Navy Ship Designations in 1920

Standard Nomenclature for Naval Vessels: General Order No. 541, 17 July 1920

U.S. Navy Ship Designations issued in 2016

Classification of Naval Ships and Craft, SECNAVINST 5030.8C

U.S. Ship Names

Ship Naming in the United States Navy

U.S. Ship Component Naming

Nomenclature of Naval Vessels

14 May 2007 - Benchmark
17 March 2009 - Added comments regarding redesignations of Mitscher class missile destroyers and extension of Arleigh Burke class DDG
17 September 2010 - Added "Old Ship" section and added information on Farragut class DLG designations
14 February 2014 - Added note about CV designation going out of use, minor changes for clarity in the cruiser and destroyer sections
01 June 2014 - Added DEC and description
30 March 2015 - Noted change from LCS to FF designation for new construction, added CVT to the Aircraft Carrier category and AFSB, JHSV and MLP to the Support Craft category, added note about Torpedo Boat renaming and corrected typographical error
14 May 2015 - Minor corrections for clarity, added SBX and YWO to Support Craft and added a mention of USS Seal / G1
20 January 2016 - Added note regarding transfer of destroyers to the US Coast Guard during prohibition
23 April 2016 - Converted to HTML 5 format
18 May 2016 - Added to the Support Craft category, added information to Minewarfare section and updated active designations for 2016
17 February 2018 - Minor changes for clarity
28 April 2018 - Added DDC type and description
09 August 2018 - Added CVHA and CVU types
17 October 2018 - Added FFR type and description
04 March 2019 - Corrected typographical error, added Expeditionary Forces section
26 June 2019 - Added EDDG type, many new auxiliary, littoral and patrol designations from the Vietnam era, new Navy Expeditionary Craft / Special Warfare Craft section, comments about meaning of "C" in "CV", the captures of ex-USS Forester and USS Pueblo, First Line Cruiser and Cruiser Minelayers, added comments and link to SECNAVINST 5030.8C, corrected hull number of USS Cushing, typographical error and updated links to off-site USN History webpages
15 May 2021 - Changed FF designation to inactive, added comment about new FFG-62 class, changed LCAC designation to active