In 1952, the U.S. Navy began a program to convert numerous light and heavy cruisers to carry anti-aircraft guided missiles. It also began a new cruiser hull number series for this new type of warship.

In January 1952 conversion began on BOSTON (CA-69) and CANBERRA (CA-70), both Baltimore Class heavy cruisers. In that both ships retained some of their original eight-inch guns they were redesignated guided missile heavy cruisers CAG-1 and CAG-2 respectively. These two ships were designated as Boston Class cruisers.

In 1957, six light cruisers were similarly redesignated as CLG-3 through CLG-8, though the first of these (USS GALVESTON) briefly retained her original number (as CLG-93). All six cruisers were converted from mothballed Cleveland Class cruisers. In this conversion GALVESTON (CL-93) became CLG-3, LITTLE ROCK (CL-92) became CLG-4, and OKLAHOMA CITY (CL-91) became CLG-5. Ships in this group were designated Galveston Class cruisers. PROVIDENCE (CL-83) became CLG-6,  SPRINGFIELD (CL-66) became CLG-7, and TOPEKA (CL-67) became CLG-8. These three ships comprised the Providence Class.

The new nuclear guided missile ship LONG BEACH was originally designated CLGN-160, then CGN-160. She received her definitive designation (CGN-9) in mid-1957. She was the sole ship in the Long Beach Class

The next three heavy cruiser conversions, ALBANY (CA-123), CHICAGO (CA-136), and COLUMBUS (CA-74), retained none of their original guns and became CG-10 through CG-12, the Albany Class.

Two more planned conversions, CG-13 and CG-14, (ROCHESTER CA-124 and BREMERTON CA-130 ) were canceled.

In 1975 all Navy guided missile frigates (DLG's) were reclassified as either guided missile destroyers (DDG), or as guided missile cruisers (CG). The CG's still under construction retained their original DLG series numbers, becoming CG-16 through CGN-41. (Note: Hull number CG-15 was skipped.)

A short time later, construction of additional un-named nuclear-powered guided missile cruisers was stopped, resulting in cancellation of the planned CGN-42.

In 1980 the new DDG-47 class guided missile destroyers were upgraded to guided missile cruisers, but retained their original numbers to become the CG-47 Ticonderoga Class. This reclassification also required skipping the intervening CG series numbers (CG-43 through CG-46). Subsequently, more than two dozen new CGs have been built and are still in service.