1,969 miles from Boca Chica, Texas, the western end of the border wall culminates in the Pacific Ocean at the major international metropolitan area of Tijuana and San Diego.

Tijuana is Mexico's fifth largest city, and the combined population of the international region is over 5 million. More than 300,000 legal border crossings occur here at San Ysidro every day.

I searched for over an hour before finding the entrance to the nearly defunct Border Field State Park that is home to the end of the border wall. The site is closed to public vehicle traffic and now crawls with Border Patrol trucks and ATVs.

I finally found my way into the park on foot, on the very day in 2010 when Mexico beat France in the World Cup. Bands played in Mexico, people sang and shouted, and hundreds played on the beach.

Meanwhile, the U.S. side of the border was empty, except for the men in green.

At one point while I was conversing with Border Patrol officers, an urgent radio call came in. They jumped on their ATVs and were gone in seconds.

Less than a minute after they had departed, a young man in Mexico slipped through the fence into the U.S. to retrieve a stray soccer ball and just as quickly went back into Mexico.