Cinco de Mayo marks Mexico’s 1862 victory over France at the Battle of Puebla. It celebrates Mexican pride and culture. Celebrated more widely also in the US, it has evolved into a festive tribute to Mexican culture,

Cinco de Mayo festivities are taking place across the U.S. with music, tacos and tequila flowing. In the U.S., the date is seen as a celebration of Mexican American culture, stretching back to the 1800s in California.

It's actually more popular in the United States than in Mexico. And it may have helped tip the American Civil War in favor of the Union.