This divided capital erupted with joy Thursday, as rebels handed over control of their territory to international peacekeepers, and American marines made their presence here known, swooping low over the city in helicopters and fighter jets.
The ear-splitting roar of machines blended with euphoric cheers in a cacophony of joy, as tens of thousands of Monrovians tried to push their way across the two bridges that have separated rebel and government territory for months.
"No more war" and "We love America," they shouted, the weight of their rejoicing causing the battle-scarred and bullet-pocked concrete bridges to shake in rhythm with their dance.
For the people of this war-weary city, Thursday's hand over was the climax of two long months of conflict here and several weeks of a painstaking crawl toward peace.
A treaty negotiated by US Ambassador John Blaney and West African military leaders oblige the rebels to pull back to the Po River, about six miles outside Monrovia. A second rebel group, based in the south, pledged to pull back to the St. John's River outside the southern city of Buchanan, Mr. Blaney said Thursday. The negotiations followed the resignation and exile to Nigeria on Monday of former President Charles Taylor.
New President Moses Blah has already offered the rebels the post of vice president as an olive branch, and was expected to hold direct talks with rebel leaders in Ghana Thursday. West African officials hope for a peace accord over the weekend.
The rebels, however, are wary of Mr. Blah, who is an old ally of Mr. Taylor, with whom he fought bush wars before the former president won elections in 1997. They have said that October, the current deadline, is too long for him to remain in power.
For the first time since 18 US troops were killed in a peacekeeping operation in Somalia, American forces are on the ground in an African conflict zone, on a humanitarian mission that could potentially bring them into combat situations.
Unlike Somalia, however, where the US presence was resented by locals, Liberians greeted the arrival of the marines with unrestrained joy.
"I am thrilled by the presence of the Americans," shouts Jonathan Bright, over the roar of the fighter jets making another flyby. "I hope they stay for a long time. Then we will be happy because we have peace. But we wish they had come sooner because many people have died here."
The US presence here is still small - just 300 marines - of which 200 arrived Thursday morning just before the bridges were handed over. American officials stress that the marines are here primarily to support the West African peacekeepers and to help with the distribution of humanitarian aid.
The extent and duration of America's role here is still unclear, although President Bush has emphasized that it will be short. It is very likely that American troops, from the 26th Marine Expeditionary Unit, will spend most of their time in Liberia at Roberts Field International Airport, about 25 miles outside the city. Some troops may stay for as little as a week and others may remain just over night.
Most of the 200 troops will comprise a rapid-reaction force that can be deployed to help the battalion of Nigerian peacekeepers who arrived here last week. A second Nigerian battalion is due to arrive soon, followed by troops from several other West African countries and eventually a UN-authorized peacekeeping force. American troops may stay only until the second batallion of Nigerians arrive. US Navy SEALS will inspect the port and American military engineers will help make it operational again.
For now, however, the 850 West Africans here - known as ECOMIL - are stretched thin. Without the help of the US, the West Africans would probably have had difficulty taking control of and securing the rebel-held portion Monrovia. Even in the part of Monrovia held by the government, only a few peacekeepers have been on the ground.
Despite the throng of Monrovians who congregated at the river, hoping to cross over to buy food or reunite with family members, Nigerian peacekeepers said they would not open the bridges to civilian traffic for at least a day, until they had fully secured the other side.
But the hand over of the bridges and Monrovia's port is good news for humanitarian organizations, who say they can begin feeding hungry Liberians within a matter of days, if sufficient food stocks remain at the port. In the runup to the hand over, a frenzy of civilians and rebel soldiers tried to haul away what remained of food supplies there.
For US troops here, the desperate humanitarian situation in Monrovia is the best reason for their involvement, although they may never see many of the people they have come to help.
As they marched across the desolate airstrip of the Roberts Field Airport, members of the 26th Marine Expeditionary Unit said they were looking forward to going home soon.
But they also said they hoped to help play a role in stabilizing the situation here, which they have been watching on CNN from their three ships off the Liberian coast. "They just need help," says Cpl. Jorges Rosado, a communications officer from New Jersey, who recently spent a tour in Iraq. "They just need a little stabilization."
• Material from the wires was used in this report.