PORTLAND, Ore. (AP) — Green Thumb Industries had a business plan, expertise and plenty of ambition to grow its marijuana business. What the Chicago-based company didn't have was access to enough capital to make it all happen.

So last month, the company with $20 million in revenue from pot shops in seven states turned its gaze north and went public in Canada, where marijuana soon will be broadly legalized nationwide.

The Canadian Securities Exchange is quickly becoming the go-to place for U.S. cannabis companies orphaned by their own stock exchanges because the U.S. government still considers m...