William and Jemima Ross originally built Ross House on the shores of the Red River at the foot of Market Avenue. William's father Alexander had provided the land. At one time the Ross home became the first post office west of Thunder Bay other than those run by the Hudson's Bay Company.

In 1949, the Manitoba Historical Society, in conjunction with the City of Winnipeg, took possession of Ross House and moved it to Higgins Avenue, across from the former Canadian Pacific Railway passenger station.

The museum was moved to its current location at 140 Meade Street (Joe Zuken Heritage Park, Point Douglas) in 1984.

The construction of Ross House is a prime example of a Red River frame building. The building itself is as much a part of the Museum as the artifacts it contains. It is made almost entirely of oak timber. All the logs used for construction were hand carved.

The Museum hosts an interpretive exhibit as well as rooms set to reflect the life of the Ross family when their home served as the post office.

William was the second son of Alexander and Sarah Ross. He was born in the Columbia River area of the Rockies in 1825. He journeyed eastward with his family when Alexander decided to retire to a more settled life in the Red River Settlement.

William was appointed Sheriff of Assiniboia in 1851 and in 1855 became the first Postmaster for the Red River Settlement. After living in the house for a mere two years William died in May 1856.

Stamps and canceling devices were unavailable at Ross House. Early mail bore only the postmaster's penned notation, "Red River, B.N.A." The monthly mail was carried by various means of transportation to Pembina, North Dakota, on the U.S./Canada border. Here it was stamped, "Paid 10" and continued to its destination.