Why Long Beach was the last purpose-built US cruiser hull

Why was USS Long Beach the last US cruiser built on a cruiser hull?

Because the later purpose-built strike cruisers were not approved and completed, leaving Long Beach as the last realized cruiser-hull design.

Long Beach remained the last completed American cruiser based on a purpose-designed cruiser hull because the later strike-cruiser proposals were never built. Congress would not approve another purpose-built cruiser. The exchange shows how political labels and procurement approval can shape fleet architecture as much as naval design requirements.