NEW YORK - The Vancouver Whitecaps and Toronto FC must have at least three Canadians on their Major League Soccer rosters this season.

MLS made the announcement today.

Last season there were no rules governing how many Canadians Toronto FC had to include on its roster.

The Whitecaps are playing their first MLS season this year. The Montreal Impact will join the league next year.

The league also announced that the Houston Dynamo will move to the Eastern Conference from the Western Conference to make room for Vancouver and the Portland Timbers, who are also joining the league this season.

Toronto FC plays in the Eastern Conference.