Which ship was the last purpose-built US cruiser hull?

Which class should be considered the last real cruiser hull in the US Navy?

USS Long Beach is the choice for the last purpose-built US cruiser hull, though other navies built later cruisers.

A purpose-built cruiser hull is separated from later ships that inherited cruiser duties or designations. USS Long Beach is identified as the last US Navy hull conceived unmistakably as a cruiser. Russian construction produced substantial cruiser designs later, so the answer is specific to the US lineage. The exchange distinguishes hull conception and institutional classification from the much broader cruising role.