The 1930 treaty changed the administrative label attached to Portland and Indianapolis while they were under construction. Both ships had been conceived as fast cruisers with eight-inch guns and carried CL designations. Once gun calibre became the dividing line, they became CAs without any matching redesign of their protection. The later New Orleans redesign added armour, while Wichita came closer to the balance expected of a heavy cruiser.
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How a treaty reclassified the Portland class
The Portland class was conceived as eight-inch light cruisers, then reclassified during construction after the 1930 treaty defined cruiser categories by gun calibre.