Douglas had been chief engineer at Martin before leaving to establish Davis-Douglas Company in early 1920 in Los Angeles. He bought out his backer and renamed the firm the Douglas Aircraft Company in 1921. McDonnell founded J. S. McDonnell & Associates in Milwaukee, Wisconsin in 1926. His idea was to produce a personal aircraft for family use. The economic depression from 1929 ruined his ideas and the company collapsed. He worked at three companies with the final being Glenn Martin Company in 1933. He left Martin in 1938 to try again with his own firm, McDonnell Aircraft Corporation, this time based at Lambert Field, outside St. Louis, Missouri.