BAGHDAD, Iraq — In front of a blue metal gate, women in black abayas clutch food ration cards and exhibit a confidence rarely felt in the Iraqi capital.

They will feed their families tonight. Several yards away, men sit behind wooden desks poring over hundreds of colorful folders, one each for Shiite families forced to flee their homes. Every family will be given a new life.

This busy office in the heart of the vast Shiite slum of Sadr City is not an arm of the government of Prime Minister Nouri al-Maliki. Nor is it a relief agency. It is the domain of the 33-year-old Shiite cleric Muqtada al-Sadr. Here, al-Sadr doles out aid to his neediest followers, from cradle to grave, filling a void in a desperately uncertain country.

“We get no help from Maliki. Only Sayyid Muqtada helps us,” said Saleh al-Ghathbawi, using the honorific that signifies al-Sadr’s descent from the prophet Muhammad.

Nowhere is al-Sadr’s power more visible than in the sprawling district in eastern Baghdad that bears his family’s name. His militiamen have made Sadr City into the safest, most homogenous enclave in a capital scarred by war and ruled by a fragile government. It often appears to operate like a separate nation, where al-Sadr’s words carry the weight of law.

The cleric’s influence is everywhere. His representatives run the hospitals, the Islamic courts, the police, the municipal offices and the mosques. He pays for funerals and school books. He builds houses and controls inflation. He punishes the corrupt and those whose activities taint Islam or his privileged name.

“He is our marja,” said Adil Murad Ali Muhammad, a retired civil servant, referring to a supreme authority on Shiite religion and law.

Yet al-Sadr’s stronghold remains one of Baghdad’s poorest areas. Banners proclaiming the al-Sadr name overlook open sewage canals, unpaved roads and crumbling buildings.

Revitalizing his city, al-Sadr representatives say, is a key motive behind the cleric’s uneasy cooperation with his arch adversary, the U.S. military, in recent weeks. Several reconstruction projects, some U.S.-funded, are already underway.

“We’ve asked the Americans to work in Sadr City responsibly, rationally and wisely,” the district’s mayor, Rahim al-Darraji, said this month. “Because Sadr City represents the determination and resilience of Iraq.”

With a population of about 2 million, Sadr City is the source of al-Sadr’s political and religious clout. That, in turn, is pivotal to the future of his community, which he hopes to represent long after U.S. troops are gone.

At one entrance into Sadr City, a banner reads: “Enter it safely. The illuminated Sadr City.”

The area is home to fighters linked to death squads who have driven thousands of Sunnis from their houses. Yet children and young men play soccer here in parks with manicured grass. Crowds mingle in open-air bazaars without fear of a suicide bomber. Women walk alone to shop, while men have long conversations in outdoor cafes, a sign of normalcy that has vanished from most of Baghdad.

Built in the late 1950s to house Iraq’s poor, the area was later called Saddam City. After U.S. forces toppled Saddam Hussein in 2003, it was renamed Sadr City to honor Muqtada al-Sadr’s father, Mohammed Sadiq Sadr, a revered ayatollah who was assassinated in 1999 by Saddam’s security forces.

Although he lacked his father’s religious credentials, the younger Sadr gained popularity by melding Islam with fierce nationalism and by challenging the U.S.-led occupation.

Now, as sectarian strife transforms the nation, cleansing mixed areas, Sadr City is perhaps the best indicator of the Baghdad that is emerging from chaos. Here, Shiites walk, pray and converse, largely with other Shiites, basking in the trust afforded by mingling with their own sect.

As day gives way to dusk, shopkeepers don’t close. They turn on the lights. Everywhere else in the capital, curfew begins at 8 p.m. Not in Sadr City.

“We don’t have a curfew,” said shopkeeper Khadim Lilugatie, 31. “We can stay open until 1 a.m. if we want.”

Despite U.S. pressure, the al-Maliki government has not challenged al-Sadr’s authority. The prime minister, who depends on al-Sadr for political support, has publicly chastised the U.S. military for staging raids into Sadr City. American troops patrol the streets now, but U.S. generals concede that they do so with al-Sadr’s cooperation.

“If it wasn’t for the Mahdi Army, there would be a lot of problems here,” said Abdul Sattar Ali, 70, who has lived in Sadr City for four decades.

“No. No. USA,” reads graffiti scrawled on a shuttered store nearby.

Nearby, Ahmed Abu Hussein is seated in his house decorated with symbols of Shiite power and piety. A Mahdi Army commander who fought U.S. troops in Najaf in 2004, Hussein is also the al-Sadr representative in charge of distributing social services to 1,700 households in Sadr City. The Mahdi Army, he said, is a popular army, whose job is just as much to assist al-Sadr’s followers as to fight the U.S. occupation.

Hussein said he and his men are growing apprehensive about the U.S. troops.

“They want to isolate the Sadr trend from society,” he said. “They want to drag us into a war.”

All his fighters “want to fight the Americans,” he added.

Asked why they haven’t risen up, he answered matter-of-factly: “It is the order of Sayyid Muqtada Sadr. He’s telling us to avoid bringing to Sadr City the curses of war.”

Seconds later, he added, “If Muqtada Sadr orders me to leave my family and sleep on the streets, I will go.”