USS Yorktown (CV-5)
USS Enterprise (CV-6)
USS Hornet (CV-8)
Experience showed that larger carriers were better for a number of reasons including, protection, speed, and seaworthiness, but when this class was designed, the U.S. was still restrained by the 1930 Naval Treaty. So while the Navy would have preferred a 27,000 ton carrier, the Yorktown class designed and commissioned before the war came in at 20,000 tons. There were no carriers at Pearl Harbor on December 7, 1941, so the full US carrier fleet was intact after the Japanese attack that started the war. The three Yorktown carriers took the war to the Japanese in the early part of the war before the Essex class were ready. Yorktown was lost in the Battle of Midway, and Hornet was lost in the Battle of Santa Cruz. Enterprise became the most decorated ship in the U.S. Navy during WW2. For more on the Enterprise, there is a web site dedicated to the history of this ship: http://www.cv6.org
All three ships in this class were built at Newport News Shipbuilding (Virginia) with the first keel laid in May, 1934, and the third ship (Hornet) launched in December, 1940.