It's not a crime for a poor person to look for a better future. It IS a crime, however, to cross international borders illegally. No matter what your reasons, it is a crime. We have not shut our borders; in fact, about 1 million people legally come to live in the United States every year. The UK and the US are experiencing similar problems in dealing with the unchecked migration of illegal aliens within their borders. We don't mind people comming here; we're all immigrants ourselves in one way or another. What we do mind is when people blatantly ignore our laws and want us to be nice about it.
Mexicans, if you wanna come here, feel free! Just fill out the proper paperwork and wait your turn like the millions of legal immigrants who live in our country. If I illegally went to live in Mexico, I bet they'd put me in jail, deport me, or just shoot me and leave me for dead wherever they found me.