"Top five is the port, the airfield, the electrical grid, the road system and the water system," said Col. Rick Kaiser with the Army Corp of Engineers.
The American military built a new control tower at the airport. Since Sunday, 160 planes land a day instead of 30. It repaired one of the capital's damaged docks - now 150 containers can unload a day.
Sergeant First Class Jason Jacot is helping turn the lights back on in Port-au-Prince. Electricity has been down since the quake.
"They are at zero, but they are making progress," Jacot said. "They're going to try and put a transmission line on tonight."
Then there's the massive job of rebuilding. Even with world governments focused on Haiti and private charitable giving nearing half billion dollars, there's no end to suffering in sight.
Just clearing debris from Port-au-Prince will take at least a year. As many as 1 million people - one person in nine across the entire country - need to find new shelter, the United Nations estimates, and there are too few tents, let alone safe buildings, to put them in. No one is under any illusions.
"The reconstruction of Haiti will take years, there's no doubt about that," said Gordon Duguid with the U.S. State Department.
Relief agencies are rushing in 100,000 tents, a temporary solution to get Haitians off the streets before the rains come.
Haiti's government wants many of the homeless to leave the capital city of 2 million people, to look for better shelter with relatives or others elsewhere. Officials estimate that about 235,000 have taken advantage of its offer of free transport to leave the city, and many others left on their own, some even walking.
Key officials from around the world met Monday in Montreal to discuss ways to coordinate relief efforts in Haiti. U.S. Secretary of State Hillary Clinton was among those attending.
The world's nations have pledged some $1 billion in emergency aid to Haiti. Organizers of Friday night's "Hope for Haiti Now" international telethon reported the event raised $57 million, with more pledges from ordinary people still coming in.