There's no line for people who don't have very close family connections, an employer request or politically favorable refugee status. This is the great myth purported by the right, that there's a line and the people coming here illegally are line cutters. The line doesn't exist for most and where it does they'll perish waiting (ever read Steinbeck's The Grapes of Wrath?).
The vast majority of people who have come here illegally saw no other reasonable choice. They aren't here to displace "legal mexicans who stood in line" and take their job picking tomatoes for 12 hours a day for meager wages in the summer heat. I mean, they could have joined the cartel as a mule or something, but other than that they lacked opportunities in their native country. The opportunities here aren't that great either, but far better than where they came from. Let that sink in.
If you're a religious person, what's the Christian thing to do? If not, what's the Human thing to do?