The Colorado class battleships (or Maryland class, under European standards, which names a class of ship after the first unit to be completed) were up-gunned versions of the preceding Tennessee class, sharing their general design and appearance, but replacing the earlier ships' twelve / 50 caliber guns with eight / 45s to counter the Japanese Nagato class battleships, which also had eight 16-inch guns.
Built with Fiscal Year 1917 appropriations and delayed by higher priorities during World War I, two of the Colorados were the last new U.S. battleships to enter service for nearly two decades, and the last U.S. battleships ever built to use the twin turrets - the World War II ships had a uniform main battery of nine 16-inch guns (16"/45 in the North Carolina and South Dakota classes and 16"/50 in the Iowa). The fourth of the class, Washington, was the only new U.S. ship cancelled under the Washington Naval Treaty for the Limitation of Naval Armaments that had actually been launched when the treaty was signed.
The three Colorados 32,600 ton standard displacement was slightly heavier than that of the Tennessee class, and the power and accuracy of their 16-inch guns represented a notable improvement. The multi-layered anti-torpedo side protection system, armor, turbo-electric drive, and improved fire controls of the Tennessees were repeated in the Colorado, which were typical U.S. battleships of the day: robust, heavily-armed and armored but relatively slow. During the 1920s and 1930s, the five ships of these two classes were popularly known as the Battle Fleet's "Big Five."
During the early 1930s, it was intended to modernize the "Big Five," but the only work actually done produced a modest increase in anti-aircraft guns and the associated fire control systems. Two of the Colorado class were present at the attack on Pearl Harbor, Maryland escaped serious damage while West Virginia was sunk at her moorings, her side protection system overwhelmed by a more than a half-dozen Japanese torpedoes (although unlike Oklahoma she remained on an even keel). Colorado was then completing an overhaul that added additional depth to the side protection, increasing her beam to , and Maryland soon received similar improvements. Both ships were further altered later in 1942, with their "cage" mainmasts cut down and their light anti-aircraft battery increased. Later, they received new after superstructures to carry better gun directors. Following kamikaze damage in late 1944, Maryland was fitted with a sixteen-gun / 38 caliber dual-purpose secondary battery, replacing the previous mixed lot of low-angle 5-inch / 51s and high-angle 5-inch / 25s. Colorado finished her days with the original mixed second battery.
The severely-damaged West Virginia was salvaged in 1942-43, and received the same extensive modernization applied to the two Tennessees: hull widened to , greatly improved fire control systems and anti-aircraft batteries, a secondary battery of sixteen 5-inch / 38 caliber guns in twin mounts, and a completely redesigned superstructure, giving her a generally "modern" appearance resembling the South Dakota class.
These ships saw the usual wartime employment of older battleships, serving as a "fleet in being" in 1942 and 1943 and thereafter providing big-gun bombardment in support of amphibious operations. Maryland and West Virginia were present for the last fight between opposing battleships, the Battle of Surigao Strait on 25 October 1944. Laid up after the War, the three Colorado class ships were part of the Reserve Fleet until 1959, when they were sold for scrapping.
The Colorado class was part of the "Standard type battleship" concept of the US Navy, a design concept which gave the US Navy a homogeneous line of battle (very important, as it allowed the Navy to plan maneuvers for the whole line of battle rather than detaching "fast wing"s and "slow wing"s). The "Standard" concept included long-range gunnery, moderate speed of , a tight tactical radius of and improved damage control. The other Standards were the Nevada, Pennsylvania, New Mexico and Tennessee classes.