the san ysidro port of entry (aka san ysidro land port of entry or san ysidro lpoe) is the largest land border crossing between san diego and tijuana, and the fourth-busiest land border crossing in the world (second-busiest if one excludes the crossings between mainland china and its two special administrative regions) with 70,000 northbound vehicles and 20,000 northbound pedestrians crossing each day, in addition to southbound traffic. it connects mexican federal highway 1 on the mexican side with interstate 5 on the american side. the san ysidro port of entry is one of three ports of entry in the san diego–tijuana metropolitan region.