According to the United States Supreme Court, illegal immigration is a crime ( DUH) as per the Plyler v Doe decision
“Since the late 19th century, the United States has restricted immigration into this country. Unsanctioned entry into the United States is a crime, 8 U.S.C. § 1325 and those who have entered unlawfully are subject to deportation, 8 U.S.C. §§ 1251 1252 (1976 ed. and Supp. IV). But despite the existence of these legal restrictions, a substantial number of persons have succeeded in unlawfully entering the United States, and now live within various States, including the State of Texas.” HERE