It's an excuse to get drunk and party, party, party. I first encountered it in TX, although I was a native Californian and lived there the first 3 decades of my life. My understanding is that Sept. 16 (which happens to be my birthday) is the true Mexican Independence Day. What say you?
September 16, or Dieciséis is the “real” Mexican Independence day as far as I’m concerned-my 1st husband was working on engineering jobs in Mexico a couple of times on 9-16, and once when it was on a weekend, I went down to join him-the people he was working with, both Texans and Mexicans-had a huge party with fireworks, food and lots of beer and whiskey-it was great fun...