Dia De Los Muertos preparations usually start the day before, on Halloween, on October 31st.

Dia De Los Muertos started today at 12:00 am. Dia De Los Muertos is more than a day, it’s actually November 1st to November 2nd. Dia de los Muertos translates to Day of the Dead. The tradition originated in Central/South America with the Aztec people. It is still heavily celebrated in Mexico today. Families make offerings to honor loved ones who have passed. The altars are decorated with flowers, candles, photos, food etc. The offerings are intended to be shared with the deceased loved ones. The 1st of November is for honoring the deceased children and the 2nd is more geared for the deceased adults. In the U.S., death is thought of as more sad and most people don’t throw parties in graveyards in the U.S. In Mexico, they celebrate the person’s life and their cemeteries are not really thought of as a sad place. 

source: https://dayofthedead.holiday/