They don't. It is a Mexican and Mexican-American celebration.
See related questions.
Cinco de Mayo is Spanish for the 5th of May, and that is when it is celebrated.
May 5th Cinco(five in spanish) de(the in spanish) Mayo(May in spanish)
The translation would be "Felíz Cinco de Mayo." Note that Cinco de Mayo is celebrated much more in the US than in Mexico!
Cinco de Mayo (Spanish for "fifth of May") is a celebration held on May 5
Mexico, Guatemala, El Salvador, and Costa Rica. They all celebrate Cinco de Mayo. They are all Spanish. (Guatemala sometimes celebrate Cinco de Mayo, because it is not always their traditions). Mexican Americans also celebrate Cinco de Mayo.
Cinco De Mayo is celebrated on May 5th in the spanish speaking countries such as; Mexico, El Salvador, Costa Rica and sometimes in Guatemala
"Cinco de Mayo es celebrado en los Estados Unidos"
Yes. In Mexico, Cinco de Mayo is mainly celebrated in the area of Puebla, where the Battle of Puebla was won against great odds by the Mexican forces. It is more widely celebrated in the US.
Feliz cinco de mayo!
Cinco de Mayo is celebrated on May 5. It is a Mexican day of celebration for the Battle at Puebla.
Feliz Cinco de Mayo ¡Cinco feliz De Mayonesa!
The reasons Cinco de Mayo is celebrated do not change over time, though the way it is celebrated might and it may be celebrated in more places over time. It is basically a Mexican holiday that is celebrated mainly around the town of Puebla in Mexico and by Mexican-Americans in the United States.