Here’s what Cinco de Mayo has become in the U.S.: a celebration of all things Mexican, from mariachi music to sombreros, marked by schools, politicians and companies selling everything from beans to beer.

And here’s what Cinco de Mayo is not, despite all the signs in bar windows inviting revelers to drink: It’s not Mexico’s Independence Day, and it’s barely marked in Mexico, except in the state of Puebla, where the holiday is rooted in a complicated and short-lived 1862 military victory over the French.

But don’t let that spoil the party.

In Houston, ballet folklorico dancers will ring in Cinco de Mayo by stomping to traditional Mexican music in a city park. New York City will close parts of Spanish Harlem and Queens for street fairs as Mexican flags flap from apartment fire escapes and car antennas. Albuquerque honors the day with a Mariachi concert and free cab rides for those who show their love for Mexico with a little too much Dos Equis XX or tequila. Even West Des Moines, Iowa, has an all-day festival with Mexican food, artwork and live music.

The holiday has spread from the American Southwest, even though most are unaware of its original ties to the U.S. Civil War, abolition and promotion of civil rights for blacks.

Often mistaken for Mexican Independence Day (that’s Sept. 16), Cinco de Mayo commemorates the 1862 Battle of Puebla between the victorious ragtag army of largely Mexican Indian soldiers against the invading French forces of Napoleon III. Mexican Americans, during the Chicano Movement of the 1970s, adopted the holiday for its David vs. Goliath storyline as motivation for civil rights struggles in Texas and California.

Over the years, the holiday has been adopted by beer companies as a way to penetrate the growing Latino market, even as the historical origins of the holiday remain largely forgotten.