Plaza de Mayo commemorates the historic Battle of Puebla . Much of the Southwestern U.S. was once part of Mexico . Many historical sites in Texas , Colorado and beyond . Old Town San Diego is hosting the Cinco de Mayo this year .
Cinco de Mayo commemorates the 1862 Battle of Puebla . Much of the Southwestern U.S. was once part of Mexico . Explore historical sites in Texas , Colorado and beyond . Old Town San Diego is hosting Fiesta Cinco de Mayo this weekend .