Mobile, Ala., doesn't usually host presidential primary rallies. But this weekend it's expected to host a doozy. Donald Trump will take over Ladd-Peebles Stadium, usually home to high school football games on Friday nights, not presidential pep rallies. Trump's campaign shifted from a smaller venue to the stadium after seeing big demand for tickets; it expects 35,000 to attend.

That's 35,000 Trump fans in a city of 200,000 -- in a county that backed Mitt Romney by 20, 30, 50 points less than its neighbors. How's Trump going to fill seats?

As with all most things Trump, there's a level of savvy that's not immediately apparent on the surface.

Alabama is one of the so-called SEC primary states that lands early in the cycle, adding importance that Alabama doesn't usually have.

But Mobile County also lies on the Gulf Coast, one of a string of relatively populous nearby counties. It's close to other big population centers. New Orleans is only two hours away, and Tallahassee 3½ hours. For Trump fans willing to embark on a longer drive, Birmingham and Atlanta aren't too far, either. (The circles on the map below are scaled to population per county.)

Within 60 miles of Mobile, according to one online tool, 1.2 million people make their homes.

Trump's also in one of the redder parts of the country, Mobile proper notwithstanding. Those 1.2 million people voted heavily Republican in 2012.

What Trump's doing, clearly, is not just trying to hold a rally in Mobile. He's trying to show strength across the entire Deep South. If his grandiose expectations come true -- which they have a recent habit of doing -- his point will be made.