Canadian National Railway ( TSX:CNR )( NYSE:CNI ) is another excellent company that dividend investors should consider buying in a TFSA. I believe this is a great stock for your portfolio because of the importance of the railway industry. Currently, there isn't a viable way to transport large amounts of goods over long distances if not via rail. In addition, Canadian National is by far the largest railway company in Canada. It operates nearly 33,000 km of track, spanning from British Columbia to Nova Scotia.