I've always heard it starts the 1st and goes through the second but you're closer to the source there in TX so I'll take your word on it. As a kid I had to go to church on my birthday as it was a holy day of obligation in the Catholic church.
it's really a matter of interpretation, during the day on the 1st is celebrated All Saints day, which you celebrate the saints and if your named after one u celebration is a little more, till night......when it turns into the night you start to celebrate the dead or the deceased, friends, family, dogs, cats etc....then you start celebrating the Muertos into the 2nd which is the day of the dead, which you send back the dead and deceased.....in Mexico, they actually celebrate at the graves site, which they eat, drink and smoke on the deceased grave.....
I start celebrating hallows eve, personally....why you might ask...cause i was supposed to be born on Halloween, but i was stubborn, and didn't pop out till the morning of the 2nd, and i am named after a saint...