So I know that under US immigration laws, a tourist can visit the United States with a passport for up to 90 days in a year (As is the case for visiting most countries)
So I was just curious, is there a limit to the number of times you can cross the border?
Example: A Mexican citizen living in Mexico right on the US/Mexico border:
There's this bar he likes to hang out at in Texas like a half a mile from his house yet in another country all the same. So when he goes there, he walks across the bridge or whatever, shows his Mexican passport to customs, and crosses over. He returns after a few hours.
Could he do this regularly, like go to the bar in Texas a few times a week? Or is there a limited to the number of times you can cross the border in a given time frame?

