He represented the electoral district of Halifax Centre in the Nova Scotia House of Assembly from 1956 to 1960.
[1] Cowan entered provincial politics in the 1956 election, winning the Halifax Centre riding by 620 votes.
[2] He was defeated by Progressive Conservative Donald MacKeen Smith when he ran for re-election in 1960.
[3] In November 1962, Cowan was a candidate for the leadership of the Nova Scotia Liberal Party, but lost by 11 votes to Earl Urquhart.
[4] Cowan tried to regain the Halifax Centre seat in the 1963 election, but Smith defeated him by 1603 votes.