But in reality that's not all that impressive, even though Canada and Mexico make wine, as well as all 50 of the United States. Small potatoes.
For one must look at the big picture and part is this: N. America makes a lot of wine per winery, yet possesses a small number of wineries overall. Consider what percentage that a State like California makes up of those 7,000 wineries. In fact, a large majority of the wine is made from just south and east of LA to an hour north of SF. Even if you incorporate the width of the state between those areas, you'd then have pretty much the exact size of a larger wine producing country in Europe, Italy. Italy is a top 3 producer worldwide. As of 2000, the small country of Italy had 55,000 bonded wineries. Think of that the next time you ponder that combined; all three countries in N. America contain only 12-13% of the quantity of wineries they do just in Italy. Incredible!
your post reminded me of a great article I read by Michael Jackson (the renowned "beer hunter", not musician, though sadly also passed) extolling the virtues and entrepeneurialism of the US craft beer scene and the diversity of experience enjoyed by the US consumer, and comparing to Europe.
Now although the number of wineries may be relatively small compared to smaller European countries, I suspect there are definite parallels when you look at the diversity of wines that are embraced (but this is pure conjecture, of course!).