Founded upon one of the campsites used by Lewis & Clark, McGowan was originally a 'mission grant' to Father Lionnet. Patrick McGowan bought the grant and then filed a 'Donation Land Claim' just west of Chenookville.

McGowan established the first salmon packing company in the state of Washington. As the settlement and business grew, the locals called it McGowan in his honor.

Once established, the post office apparently issued several cancelers, Spellings used are: MC GOWAN and McGOWAN. The McGOWAN is seen used in 1906 and again on the last day. but the size and positioning of the letters of the name are quite different. The MC GOWAN was used in 1913.

The church built in 1904 by the McGowans, St. Mary's Catholic Church, still stands on the townsite.