Numbering: Protected Cruisers and 3rd Class Cruisers were initially numbered in a single "Cruiser" (C-x) series, Armored Cruisers in a separate series (ACR-x), and Scout Cruisers in a third series (CS-x); there were several un-numbered cruisers. In two redesignations (17 July 1920 and 8 August 1921) the Protected, 3rd Class and Scout Cruisers received new designations in the Light Cruiser ("CL xx") series, and Armored Cruisers kept their numbers but became simply "Cruisers" ("CA xx"); there was considerable swapping of categories, and many previously un-numbered cruisers received numbers. After 1 July 1930 new Heavy Cruisers ("CA xx") were numbered in the same series as the CLs; some CLs became Anti-Aircraft Cruisers (CLAA) with the same numbers 18 March 1948. Hunter-Killer Cruisers (CLK) were numbered in a separate series.

Postwar, Guided Missile Cruisers started a new series (CAG/CLG/CG). On 30 June 1975 a large number of "Frigates" (DLG/DLGN) became Guided Missile Cruisers (CG/CGN), and the remaining CLGs became CGs. Several DDGs became CGs 1 Janaury 1980.