How to have a top-flight association football (soccer) league in Canada without involving the United States

 Step 1, new league takes the three existing MLS clubs in Canada.  (3 teams)

Montreal
Toronto FC
Vancouver

Step 2.  Three teams in Toronto, 2 in Vancouver and 2 in Montreal (Adds 4 new teams, for 7)

Ontario FC
New Town FC
Montreal Maroons
BCFC

Step 3.  Expand to these 11 cities (for 18 teams)

Calgary
Edmonton
Ottawa
Winnipeg
Saskatoon
Regina
Hamilton
Victoria
Halifax
Quebec City
Niagara Falls/St. Catherine

By Provence

British Columbia-3

Vancouver Whitecaps
BCFC
Victoria

Alberta-2

Calgary
Edmonton

Saskatchewan-2

Regina
Saskatoon

Manitoba-1

Winnipeg

Ontario-6

Toronto FC
New Town FC
Ontario FC
Ottawa
Hamilton
Niagara Falls/St. Catherine

Quebec-3

Montreal
Montreal Maroons
Quebec City

Nova Soctia-1

Halifax