Mr. Frank Hoolihan was born in 1897 and is listed variously on the census records as a sailor or a waiter with the Lake Carrier's Association. His 1918 draft card signature matches this signature. Note that the postcard is addressed to the "Buffalo Dry Dock" which was a shipbuilding area that changed hands often, and was called that between about 1900 and 1914. He died in 1943. His family lived in the "sea wall squatters" area of Buffalo, and his father was apparently a local character. 

He was probably in Duluth on a ship, even as a teenager who signed up to work before his mom approved?