In most states you can buy any wine from anywhere at grocery stores.  Lack of Canadian wines in US grocery stores is more due to lack of demand, but you can find Argentinian, Chilean, French, Spanish, Italian, and Australian wines at pretty much any grocery store in the US that is allowed to sell wine.  Some states don't allow grocery store sale of wines or have a liquor percentage (In New York State it is only wines under 6% Alcohol), but generally where produced doesn't matter.