He was born in Londonderry, New Hampshire in 1825 and came to Canada West in 1849. Patterson and his brothers, operating as Patterson Brothers, manufactured agricultural equipment in the Richmond Hill area. They also operated a sawmill, gristmill, foundry and blacksmith shop. The company provided living quarters for their workers, a school and church near the factory. Peter served as reeve for Vaughan Township from 1868 to 1873. In 1886, the operation was relocated to Woodstock to gain access to cheaper transportation via rail. The company was taken over by Massey-Harris in 1891.