Mortimer Leo Downey III (August 9, 1936 – November 2, 2023) was an American government official who was Deputy Secretary of Transportation from 1993 to 2001, making him the longest-serving person to ever hold the post.

[1] After Carter's presidency ended in 1981, Downey was hired by the New York Metropolitan Transportation Authority (MTA) as an assistant executive director.

[1] The MTA's budget increased by $3 billion during his tenure, and New York Senator Daniel Patrick Moynihan once noted, "He left almost as popular as when he arrived.

[3] In 2010, Downey was appointed to the board of directors of the Washington Metropolitan Area Transit Authority, to one of the seats chosen by the federal government.

[4][5] His period as chairman was marred by poor relations with fellow board members, some of whom accused him of inefficiency, and eventually, of having a conflict of interest, due to his job as an advisor with an engineering firm which worked with the Metro.