When Howland first arrived in Upper Canada in 1830, he lived in Cooksville, Mississauga, managing a post office. His first business venture was in partnership with his brother, Peleg, beginning in 1831, selling goods. He soon occupied land just west of the Humber River, in Etobicoke. In 1840, Howland leased land on both sides of the river from Thomas Cooper, including Cooper's Mills. He renamed them Lambton Mills, which became the name of the neighbourhood itself.

​

The Lambton Mills business  did not remain Howland's top priority for very long, however, as his interests in government and finance refocused his efforts and his habitation within the heart of Toronto. In the 1850s, his brothers Peleg and Frederick would mostly take over the operations at Lambton Mills. Among many other roles, William Pearce Howland would go on to be a political influence during the turbulent years of confederation.

Linked here is a map showing the land associated with the Howland family in the Lambton mills area, as they were in 1860. Notice that the lot in which the mills are on is listed as "Wm. P. Howland & Co." indicating the partnership with brothers Peleg and Frederick.

Tremaine’s Map of the County of York Canada West, Compiled and Drawn by Geo. R. Tremaine from Actual Surveys Toronto Published by Geo. C. Tremaine 1860