Andrew was born on Christmas Day, 1808, as the son of John McReynolds and Ann Sloan.

He was also a cousin of Andrew Jackson and his grandfather was a lawyer of consummate ability and a sheriff of Tyrone County.

[1] After his father's death, he inherited his fortune and decided to move to New York in 1830 before ultimately settling in Detroit in 1833.

[1] After the start of the American Civil War, McReynolds enlisted in the Union Army and was given carte blanche to organize a cavalry regiment anywhere.

Despite his long legal career, due to being Democratic, McReynolds never managed to pursue a major office besides being the prosecutor for Muskegon county from 1874 to 1876.