What is Cinco de Mayo? Well, it's not Mexican Independence Day (think dieciséis de septiembre), even though it's an official federal holiday in Mexico.

The day actually celebrates a fleeting victory by Mexican soldiers at Puebla in 1862 that only temporarily halted an invasion by a French force that would eventually take over Mexico City and install the Emperor Maximilian.  

But these days it's more like a Mexican version of St. Patrick's Day, Oktoberfest and Chinese New Year -- especially the drinking part.

In the United States, and in places as far-flung as Malta, it's a grand occasion to drink Mexican beer ("Stay thirsty, my friends.") or margaritas (named, they say, for Margarita Cansino, who became Rita Hayworth).

So much so that Bernalillo County will extend its free Safe Ride Home program by an additional five hours tonight, in order to head off DWI crashes and fatalities among Cinco de Mayo revelers.

Safe Ride Home, normally offering free rides home for inebriated folks from 10 p.m. to 2 a.m. every Friday, Saturday and Sunday, will be offered from 10 tonight to 3 a.m. tomorrow, according to a county news release.

To get a free ride home, you must ask a restaurant or bar employee to call the Albuquerque Cab Company to schedule a ride.

The county spends 10s of thousands of dollars each year on the free rides through its DWI program.