He was born in County Leitrim, Ireland in 1825, the son of Patrick Cowan, and was educated there, earning a teaching certificate. He emigrated to North America and arrived in Bytown around 1845. He taught school in North Gower for five years. In 1850, he married Caroline McCrea; he also purchased a farm in the township around that time. Cowan was reeve for the township from 1865 to 1869. In 1866, he served as warden for Carleton County. Cowan also served as justice of the peace, was clerk in the division court for 21 years and became a captain in the local militia. In 1870, he was named secretary for the county and, in 1873, was named county treasurer. With these postings, Cowan sold his farm and moved to Ottawa, where he served on the board of Water Commissioners.
