I have seen my grandparents immigration route before but now I Cant find it , they were from mexico
Please have a look at wiki and see if that is what you are looking for - please scroll down the page
https://www.familysearch.org/wiki/en/index.php?search=mexico%20immigration&title=Special%3ASearch&fulltext=1&ns0=1&ns12=1&ns14=1&ns102=1&ns108=1&ns3100=1
