Getting American forces out of Iraq is a major logistical undertaking. The U.S. is emptying about 300 bases throughout the country. So far, 10,000 vehicles and 76,000 other pieces of equipment have been shipped out. This involves moving as many as 300,000 shipping containers a month out of the country. When the withdrawal is complete, in about a year, over 1.5 million items of equipment (from artillery to generators, to radars and so on) will have been moved, along with thousands of tons of supplies. This, despite giving thousands of vehicles, and even more items of equipment, to the Iraqi security forces. Some of the troops, and a lot of the equipment, is being shipped to Afghanistan.
At its peak, there were over 200,000 American troops in Iraq. Now there are 100,000, and that will be down to 50,000 by August. At that point, all the American troops remaining will be trainers and advisors for the Iraqi army and police.