The Montana class battleship was designed to be the successor to the four Iowa class fast battleships in service during World War II, a further two Iowa class battleships were under construction but scrapped at the end of the war.
As was expected with the Montana-class if completed, Midway-class aircraft carriers were the first US Navy ships too big to transit the Panama canal. Description from operatorchan.org. I searched for this on bing.com/images
USS Montana (BB-67) was never built. Had the Montana-class Battleships been built, they would have been the largest, best protected and the most heavily armed Battleships put to sea by the United States. They would have been the only US Navy battleship to have rivaled the Imperial Japanese Navy's Yamato-class Battleships in terms of armor, weaponry and displacement.