Today is CINCO DE MAYO, celebrated in the United States and in Mexico, primarily in the state of Puebla, where the holiday is called El Día de la Batalla de Puebla (English: The Day of the Battle of Puebla).

It originated with Mexican-American communities in the American West as a way to commemorate the cause of freedom and democracy during the first years of the American Civil War, and today the date is observed in the United States as a celebration of Mexican heritage and pride. In the state of Puebla, the date is observed to commemorate the Mexican army’s unlikely victory over French forces at the Battle of Puebla on May 5, 1862, under the leadership of General Ignacio Zaragoza Seguin. Cinco de Mayo is not Mexico’s Independence Day—the most important national patriotic holiday in Mexico—which is celebrated on September 16.

The American Cinco de Mayo celebration originated in the Mexican-American communities of the American West, Southwest, and Northwest in the 1860s. Mexicans and Latinos living in California during the American Civil War are credited with being the first to celebrate Cinco de Mayo in the United States. It grew in popularity and evolved into a celebration of Mexican culture and heritage, first in areas with large Mexican-American populations, like Los Angeles, Chicago and Houston. Eventually it expanded across the United States.

On June 7, 2005, the U.S. Congress issued a Concurrent Resolution calling on the President of the United States to issue a proclamation calling upon the people of the United States to observe Cinco de Mayo with appropriate ceremonies and activities.

According to a paper published by the UCLA Center for the Study of Latino Health and Culture about the origin of the observance of Cinco de Mayo in the United States, the modern American focus on that day first started in California in the 1860s in response to the resistance to French rule in Mexico. “Far up in the gold country town of Columbia (now Columbia State Park) Mexican miners were so overjoyed at the news that they spontaneously fired off rifles shots and fireworks, sang patriotic songs and made impromptu speeches.”

A 2007 UCLA Newsroom article notes that “The holiday, which has been celebrated in California continuously since 1863, is virtually ignored in Mexico.” TIME magazine reports that “Cinco de Mayo started to come into vogue in 1940s America during the rise of the Chicano movement.” The holiday crossed over from California into the rest of the United States in the 1950s and 1960s but didn’t gain popularity until the 1980s when marketers, especially beer companies, capitalized on the celebratory nature of the day and began to promote it.