Mexicans who immigrate here legally are welcomed but there is also the corrupt Mexican government's Program for Mexican Communities Abroad. Its unwanted citizens are being herded across the border. The corrupt Mexican government expects, however, that those citizens remain loyal Mexicans and meddles in our affairs to promote that end. Mexico considers itself to be a nation without borders -- a kind of Mexican diaspora. google has tons of links.
The corrupt Mexican government's consulate personnel and corrupt Mexican government's corrupt state governments are also active in creating home town associations (HTA) or "clubs" here in the U.S. that fund projects and public services in the corrupt home towns back in Mexico. google has tons of links. Gee, how do Mexican citizens have so much money left over to send home to family and government? Why don't we just have the various social services send the checks directly to the corrupt Mexican government?
I have found that there is very little interest in viewing ILLEGAL immigration from this angle. In practice it is "legal" because both of our political parties want it and likely have agreements with the corrupt government of Mexico.
The only way to stop ILLEGAL immigration is to stop it at the source: the Democrat and the Republican Party leadership.