Tukwila, Washington - 1960's
I see this listed as Westfield "Shoppingtown" Southcenter, a lot now (though not on this postcard). Not sure if that "Shoppingtown" part is a newer moniker, or if it's always been called that.
Either way, here's a nice shot of an old Penneys, and the parking lot with all those glorious '60s cars down there! Their current website.