The city was formed in 1970 by the merger of the smaller cities of Fort William and Port Arthur. Fort William, originally the French Fort Caministogoyan, was the hub of the North West Company's fur trading business in the early 19th Century. Port Arthur, a few miles to the north, was first settled in 1870 as the head of construction of the Dawson Road connecting Ontario with Western Canada.
Forestry and manufacturing are the largest industries in Thunder Bay, with Bowater Forest Products and Bombardier Transportation maintaining large operations there.
Thunder Bay is home to two institutions of higher learning: Lakehead University and Confederation College.
In 1995, Thunder Bay hosted the World Nordic Ski Championships.