From El Golfo, you head straight north to San Luis del Rio Colorado. Theres a port of entry there, its open 24 hours a day but its usually busy. If the border wait is busy you can head west of Mex Hwy 1 to Mexicali. There are two ports there, but the streets of Mexicali to each Port is confusing if you have never been there before...Mexicali is a big city.