The self-unloading schooner-barge Transfer began its career as the William McGregor. The schooner-barge was launched in 1872 at the Linn & Craig shipyard in Gibraltar, Michigan. The vessel was first enrolled at the port of Detroit, Ohio under the official number 80268. The vessel was described as having one deck and three masts measuring 200 feet in length, 33.9 feet in beam, and 13.7 feet in draft with a carrying capacity of 732.94 tons.

The William McGregor was built for the Northwestern Transportation Company of Detroit and was purposely built to be towed by the steamship R.J. Hackett, what is arguably the first purposely built bulk freighter, in the bulk cargo trade.

for thirty-eight years the schooner-barge engaged in carrying iron ore between Lake Superior mines and Lake Erie ports, until 1911 when it was sold to the Milwaukee-Western Fuel Co. of Milwaukee. After it's purchase the vessel was renamed Transfer, rebuilt as a tow barge, equipped with self-unloading machinery, and used specifically in Milwaukee's riverways transporting coal between coal yards and powerhouses. In 1915 the Transfer was purchased by the Milwaukee Electric Railway and Light Co. and used to transport coal to the company's powerhouses, the Commerce street plant, Oneida street plant, and Commonwealth plant. During its twelve-year service as a coal barge Transfer made 1,525 round trips between coal docks and power houses carrying a total of around 1,830,000 tons of coal.
On December 6, 1923, the Milwaukee Electric Railway and Light CO. decided to purchase another vessel, the E.M.B.A., and retire the Transfer. Anything of value was removed from the vessel, the barge's windows were smashed in, and it was towed six miles out of the harbor where it was set adrift and rammed three times until it sank.
The Transfer shipwreck site was located by Captain Jerry Guyer in 2009. Wisconsin Historical Society maritime archaeologists and volunteers surveyed the site in August 2019. The remains of the self-unloading schooner-barge lie broken on an even keel in 120 feet of water, 6.0 miles southeast of the main Milwaukee harbor entrance in Lake Michigan. The vessel remains broken, though most of it's construction components and artifacts remain within the vessel's broken hull. The wreckage sits relatively flat on the lake bottom. the starboard side is splayed outward and the port side has collapsed in on itself covering a portion of the wreck. the sternpost still stands 11.0 feet off of the bottom of the lake. There is an abundance of disarticulated timbers around the wreck due to its violent means of sinking. The Transfer is one of three known self-unloading barges in Wisconsin waters.