CANADA: CP’s railway to riches?

"With a big U.S. investor on board, CP (Canadian Pacific) faces a boardroom battle as it rushes to catch rival CN."

CN (Canadian National) has a big U.S. investor on board too... Bill Gates.
"The largest shareholder of CN, the bigger of Canada’s two railways, is none other than Microsoft co-founder and former CEO Bill Gates, who owns about 10 per cent of CN’s stock."

Why are U.S. investors buying Canadian owned businesses?