Who was the first US man to orbit the earth?

The first US astronaut to orbit the Earth was John Glenn, aboard the Mercury capsule he named Friendship 7, on February 20, 1962. He was preceded by the 1961 sub-orbital flights of Alan Shepard and Gus Grissom.

First Man in SpaceYuri Alekseyevich Gagarin (9 March 1934 - 27 March 1968), beat Glenn to the honor by 314 days. On 12 April 1961, the Soviet cosmonaut became the first human in outer space and the first to orbit the Earth.