WASHINGTON, Jan 4 (Reuters) - Japanese automaker Toyota Motor Corp (7203.T) outsold General Motors Co (GM.N) in the United States in 2021, marking the first time the Detroit automaker has not led U.S. auto sales since 1931. Toyota sold 2.332 million vehicles in the United States in 2021, compared to 2.218 million for General Motors, the automakers said Tuesday. GM"s U.S. sales were down 13% for 2021, while Toyota was up 10%. For all of 2020, GM"s U.S. sales totaled 2.55 million, compared with Toyota"s 2.11 million and Ford"s 2.04 million.