American forces leaving Iraq are headed in two directions. Most of the troops and equipment go west, to the United States. But a lot of them, along with their equipment, go east, to Afghanistan. Much of the stuff going east has to do with intelligence gathering and dealing with roadside bombs. This includes dozens of UAVs and even more camera systems (both tower mounted, and carried by tethered blimps.) These systems enable operators to maintain a secure zone within 10-20 kilometers of a base, because roads and terrain can be monitored at all times.
The U.S. is closing down over 300 bases throughout the country. About half the job is done so far, with the "items of equipment" (artillery, generators, radars, rifles, radars and so on) down from a peak of 3.4 million to 2.2 million. That will fall to a million items in four months. There are only about 29,000 vehicles left, down from 41,000. Many are given to Iraqi forces, but most are being shipped east or west (often getting a refurbishment in Kuwait or other Gulf nations first.) Troops strength will fall from 90,000 to 50,000 over the next four months. At that point, all the American troops remaining will be trainers and advisors for the Iraqi army and police. At its peak, there were over 200,000 American troops in Iraq.