Shopping in Tijuana can make a great day-long activity for those visiting San Diego. (Photo credit: Robert Arends) RELATED LINKS Return to San Diego City Guide

Many travelers to San Diego also visit to the bustling Mexican border town of Tijuana about 20 miles to the south for shopping, dining and nightlife. United States citizens can cross into Mexico with only a valid driver's license, birth certificate or other proof of citizenship, and unless you plan to stay more than 72 hours or travel farther south into Mexico, no further documentation is required. U.S. currency is accepted all over town, so there's no need to change dollars into pesos.

The easiest way to get to Tijuana is to drive or take the blue line trolley to San Ysidro on the U.S. side of the border and cross into Mexico on foot or by bus. If you choose to drive across the border, bear in mind that many car rental contracts do not allow vehicles to be taken out of the U.S. Whether you're driving your own car or a rental, you'll need to stop in San Ysidro to purchase a Mexican auto insurance policy for the duration of your stay. Keep the policy with you at all times, along with documents proving ownership and registration of the vehicle. Also be aware that while the southbound border crossing usually moves quickly, motorists often have to queue up for an hour or two to get back into the U.S.

As in any big city, a certain amount of street smarts is in order. Get too loopy on margaritas and you'll be seen as an easy target for pickpockets and other opportunistic criminals. And finally, beware of bargain pharmacies that specialize in selling cheap drugs to tourists. Purchasing controlled medications without a legitimate prescription from a licensed physician is a serious crime in Mexico, and you really don't want to see the inside of a Tijuana jail.