Seven of the 19 Islamic terrorists who hijacked commercial planes on September 11, 2001 (9/11), killing nearly 3,000 Americans, remained in the United States after overstaying their visas thanks to a wide-open loophole that continues to allow about 685,000 illegal aliens to stay in the U.S.

In total, all 19 terrorists arrived legally in the U.S. as 16 secured tourist visas and three obtained business and student visas. Eventually, on September 11, the terrorists executed attacks in New York City, New York, Washington, DC, and Pennsylvania that killed 2,977 Americans and have since left thousands more Americans dead with illnesses related to the attacks.

Seven of the 19 terrorists overstayed their visas either before the attacks or at the time of the attacks. Despite U.S. immigration law requiring their detainment and potential deportation, none were detained or deported.