Besides the larger retail malls, there seems to be larger house lots in the U.S. as well. I observe that there seems to be more quasi-rural living, where people seem to be in rural settings, and commute to the city for work. As we drive around the Philadelphia area, that is the impression one has.
I found an article by Moya K. Mason that looked at house sizes over the last few centuries. In the 1800s a large home ranged between 2200 and 2800 square feet. That's the size of suburban American and Australian homes today.
In terms of lot sizes, these seem to be shrinking since 1990 in the U.S. where the average size of a house is increasing and its lot is decreasing. Reports have the size between 12,870 square feet and 15,456 square feet or .35 acres.
There doesn't seem to be any information for Canada to make a comparison, so I guess my anecdotal experience will have to do for now.
Here are two scenes from a building on the grounds of the Hagley Library, in Wilmington, Delaware.