McPherson, Jeb Stuart and John B. Gordon were of Scottish descent, George B. McClellan and Stonewall Jackson Scotch-Irish. Douglas MacArthur and George Marshall upheld the martial tradition in the twentieth century. Grace Murray Hopper, a rear admiral and computer scientist, was the oldest officer and highest-ranking woman in the U.S. armed forces on her retirement at the age of 80 in 1986. Isabella Cannon, the former Mayor of Raleigh, North Carolina, served as the first female mayor of a U.S. state capital. Automakers The Scottish-born Alexander Winton built one of the first American automobiles in 1896, and specialized in motor racing. He broke the world speed record in 1900. In 1903, he became the first man to drive across the United States. David Dunbar Buick, another Scottish emigrant, founded Buick in 1903. The Scottish-born William Blackie transformed the Caterpillar Tractor Company into a multinational corporation. Motorcycle manufacturer Harley-Davidson Inc (formerly HDI), often abbreviated "H-D" or "Harley", is an American motorcycle manufacturer. The Davidson brothers were the sons of William C Davidson (1846-1923) who was born and grew up in Angus, Scotland, and Margaret Adams McFarlane (1843-1933) of Scottish descent from the small Scottish settlement of Cambridge, Wisconsin. They raised five children together: Janet May, William A., Walter, Arthur and Elizabeth. Aviation Scottish Americans have made a major contribution to the U.S. aircraft industry. Alexander Graham Bell, in partnership with Samuel Pierpont Langley, built the first machine capable of flight, the Bell-Langley airplane, in 1903. Lockheed was started by two brothers, Allan and Malcolm Loughead, in 1926. Douglas was founded by Donald Wills Douglas Sr. in 1921; he launched the world's first commercial passenger plane, the DC-3, in 1935. McDonnell Aircraft was founded by James Smith McDonnell, in 1939, and became famous for its military jets. In 1967, McDonnell and Douglas merged and jointly developed jet aircraft, missiles and spacecraft. Spaceflight Scottish Americans were pioneers in human spaceflight. The Mercury and Gemini capsules were built by McDonnell. The first American in space, Alan Shepard, the first American in orbit, John Glenn, and the first man to fly free in space, Bruce McCandless II, were Scottish Americans. The first men on the moon, Neil Armstrong and Buzz Aldrin, were also of Scottish descent; Armstrong wore a kilt in a parade through his ancestral home of Langholm in the Scottish Borders in 1972. Armstrong's ancestry can be traced back to his eighth paternal