Canadian Firms on the Prowl

Land developers and oil drillers lead a move south

The Silver Triangle in downtown Denver is a 20-square-block collection of parking lots, seedy hotels and aging, rundown stores. But a few months ago, the area started blossoming with bright green and white signs reading: ACQUIRED FOR CLIENTS. KNOWLTON REALTY, LTD.

Knowlton is a Calgary, Alta., real estate firm that over the past year bought up $70 million worth of Triangle property as part of the major new influx of Canadian investment into the U.S.

Canadian firms have long done business in the U.S. The Bank of Montreal helped start the Chicago Clearing House in...