KHABARI CROSSING, Kuwait -- As their convoy reached the barbed wire at the border crossing out of Iraq on Wednesday, the soldiers whooped and cheered. Then they scrambled out of their stifling hot armored vehicles, unfurled an American flag and posed for group photos.

For these troops of the 4th Stryker Brigade, 2nd Infantry Division, it was a moment of relief fraught with symbolism. Seven years and five months after the U.S.-led invasion, the last American combat brigade was leaving Iraq, well ahead of President Barack Obama's Aug. 31 deadline for ending U.S. combat operations there.

When Spc. Luke Dill first rolled into Iraq as an 18-year-old as part of the U.S. invasion, his Humvee was so vulnerable to bombs that the troops lined its floor with flak jackets.

Now 25 and a staff sergeant after two tours of duty, he rode out of Iraq this week in a Stryker, an eight-wheeled behemoth encrusted with armor and add-ons to ward off grenades and other projectiles.

"It's something I'm going to be proud of for the rest of my life, the fact that I came in on the initial push and now

I'm leaving with the last of the combat units," he said.

He remembered three straight days of mortar attacks outside the city of Najaf in 2003, so noisy that after the firing ended, the silence kept him awake at night.

He recalled the night skies over the city of Mosul being lit up by tracer bullets from almost every direction.

Now, waiting for him back in Olympia, Wash., is the "Big Boy" Harley-Davidson he purchased from one of the motorcycle company's dealerships at U.S. bases in Iraq, a vivid illustration of how embedded the American presence has become since the invasion of March 20, 2003.

That presence is far from over. Scatterings of combat troops still await departure, and some 50,000 will stay another year in what is designated as a noncombat role. They will carry weapons to defend themselves and accompany Iraqi troops on missions, but only if asked. Special forces will continue to help Iraqis hunt for terrorists.

So the U.S. death toll, at least 4,415 by Pentagon count as of Wednesday, may not yet be final.

The Stryker brigade, based in Joint Base Lewis-McChord in Washington state and named for the vehicle that delivers troops into and out of battle, has lost 34 soldiers in Iraq.

It was at the forefront of many of the fiercest battles, including operations in eastern Baghdad and Diyala province, an epicenter of the insurgency, during "the surge" of 2007. It evacuated troops at the battle of Tarmiyah, an outpost where 28 out of 34 soldiers were wounded holding off insurgents.

Before the Aug. 31 deadline, about half the brigade's 4,000 soldiers flew out like most of the others leaving Iraq, but its leadership volunteered to have the remainder depart overland. That decision allowed the unit to keep 360 Strykers in the country for an extra three weeks.

U.S. commanders said it was the brigade's idea, not an order from on high. The intent was to keep additional firepower handy through the "period of angst" that followed Iraq's inconclusive March 7 election, said brigade chief, Col. John Norris.

It took months of preparation to move the troops and armor across more than 300 miles of desert highway through potentially hostile territory.

The Strykers left the Baghdad area in separate convoys over a four-day period, traveling at night because the U.S.-Iraq security pact -- and security worries -- limit troop movements by day.

Along the way, phalanxes of American military Humvees sat at overpasses, soldiers patrolled the highways for roadside bombs, and Apache attack helicopters circled overhead as the Strykers refueled alongside the highway.

But except for camels straying onto the road, and breakdowns that required some vehicles to be towed, there were no incidents.

The worst of the ride were the conditions inside the Strykers, sitting for hours in a cramped space, and the temperatures outside that reached 120 degrees.

When the convoy finally reached the sandy border, two soldiers, armed and helmeted, jumped off their vehicle and raced each other into Kuwait.

Once out of Iraq, there was still work to be done. Vehicles had to be stripped of ammunition and spare tires, and eventually washed and packed for shipment home.

For Dill, who reached Kuwait with an earlier convoy, the withdrawal engendered feelings of relief. His mission, to get his squad safely out of Iraq, was accomplished.