Army Captain Christopher Ophardt, spokesman for the 4th Stryker Brigade, 2nd Infantry Division, said the last of the unit's vehicles crossed the border into Kuwait early on August 19.
It was a heavily symbolic departure, and a television crew from the U.S. cable news network MSNBC rode with some of the departing troops, broadcasting the border crossing live as it happened.
But a smattering of combat troops still remain in Iraq, and a senior White House official told Reuters on August 18 that media outlets who reported that combat operations had ended were wrong. The official said that won't happen until August 31.
As of now, there are still 56,000 U.S. troops in Iraq. By September 1, 50,000 will still be in place, in noncombat roles technically classified as "advise-and-assist brigades."
The Pentagon says some troops will accompany Iraqi patrols on missions, if requested, and some will continue to train Iraqi armed forces and police units. Special forces will continue to help Iraqis track down terrorists.
The remaining U.S. troops are set to leave Iraq at the end of December 2011.
More than seven years have passed since the U.S.-led invasion toppled Iraqi dictator Saddam Hussein, in March 2003. The official U.S. death toll now stands at 4,419.
The Iraq Body Count project -- which tracks violent deaths of Iraqi civilians since the U.S. invasion using media reports and records from hospitals, morgues, and NGOs -- puts the number of Iraqi deaths around 100,000.
The Iraq war has lasted longer than the U.S. Civil War, World War I, and World War II.
The outgoing U.S. ambassador to Iraq, Christopher Hill, told an audience at the U.S. Institute of Peace on August 18 that things in Iraq were "definitely going in the right direction."
"The security situation, which is very difficult and one that is not going to be at a completely satisfactory level, will continue to improve. The Iraqi forces are capable of handling the security problems. They will have problems. There will be mistakes," Hill said.
"We have made mistakes, too, in how we handled it. They will learn from their mistakes as we learned from our mistakes and I think you will see a continued improvement in the security situation."
As Hill spoke, five Iraqi government workers were killed in roadside bombings and other attacks by insurgents. A day earlier, a suicide bomber killed 61 army recruits in Baghdad.
And five months after elections, the two main political blocs have yet to form a governing coalition.
The violence and political chaos are a stark reminder of the uncertain situation U.S. forces are leaving behind.
written by Heather Maher with agency reports.