Walsh a lawyer scholar and former govt. worker makes an excellent case for huge number of illegals crossing the borders and also includes numbers form Canada as well. My estimate of 38 million illegal aliens residing in the United States is calculated, however, using a conservative annual rate of entry (allowing for deaths and returns to their homelands) of three illegal aliens entering the United States for each one apprehended. My estimate includes apprehensions at the Southern Border (by far, the majority), at the Northern Border, along the Pacific, Atlantic, and Gulf of Mexico coasts, and at seaports and airports. Taking the DHS average of 1.2 million apprehensions per year and multiplying it by 3 comes to 3.6 million illegal entries per year; then multiplying that number by 10 for the 1996–2005 period, my calculations come to 36 million illegal entries into the United States. Add to this the approximately 2 million visa overstays during the same period, and the total is 38 million illegal aliens currently in the United States. Illegal Aliens: Counting the Uncountable is the book.
The last stats I saw,don’t have a link handy, suggested that a little over 50% of the illegals were of Mexican decent.
The rest come from central, South America,The Caribbean, and the rest of the world. Mexico being such an easy entry into the US illegals from all over the world use it as an entry point.