Until 2007 McCown served in several leadership roles during both terms of George W. Bush's presidency in Washington D.C. Appointed initially to the U.S. Senior Executive Service by Democratic Transportation Secretary Norman Y. Mineta, (D-CA) he was later reappointed by Republican Transportation Secretary Mary Peters, (R-AZ). McCown initially worked as the first chief counsel (general counsel) of the Federal Motor Carrier Safety Administration (FMCSA), where he was responsible for legal oversight of the nation's trucking, motor coach, moving industry and NAFTA. During this time, He advocated for stronger truck and bus safety regulations, including better oversight of the commercial bus industry and the requirement for all buses to be equipped with seat belts.