After 9/11/01, when Bush decided to bring the federal law enforcement world a little closer together, he formed the Department of Homeland Security(DHS). Border Patrol, Customs, Immigration and VERY small portions of FBI, NSA, and CIA were placed under DHS. This was done because of poor communication, lack of cooperation, and overlapping jurisdictions. There are several branches of DHS and ICE is one of them. Immigration and Customs Enforcement is ICE. All of the Immigration agents and Customs agents were cross trained to do each others' jobs. This way they can work together as teams and get more work done.

There are other branches like border protection which includes border patrol, immigration inspectors, and customs inspectors. The inspectors are the people staffing the checkpoints and border crossings. The agents are the LE officers who actually investigate the criminal violations of the laws.

The branches have changed names like two or three times since DHS took over, but ICE seems to have stuck.