Both; it is a common celebration just as Halloween is to US.
It is a Hispanic holiday so Mexico is where it is very important.
Day of the dead is equally important in the north and south. It is a religious tradition of remembrance, not a regional one.
Southern Mexico
Because it is a mix of ancient Native American and Spanish traditions; northern Mexico was almost unpopulated and no traditions like this were known at the time, as it was inhabited by semi-nomadic groups without extensive cultural traditions. Before Spanish conquistadors conquered Mexico in the 16th century, a kind of Day of the Dead was celebrated by Aztec and Mayan societies, celebrating the children and the lives of people who had passed away. When Spain conquered Mexico in 1521, they merged their own All Souls Day with the already existing tradition, thus becoming Day of the Dead.
rural America, northern Mexico, and urban America
rural
rural
Northern 360,000 dead, Southern 260,000 dead. These are best estimates; exact figures are not possible. There would have been about two to three times that many wounded. On both sides disease killed two of these for every one the enemy did.
Sugar skulls are made in central and southern Mexico, as part of the Day of the Dead (November 1 and 2) celebration.
It takes place in parts of Texas and across the border in Mexico. the great plains is Northern Texas.
In Mexico they celebrate the dead on Nov. 1-2.
The day of the dead in Mexico is November 1 and 2.