(Adds evacuation order, updates with Trump tweets, Irma details)

By Steve Holland and Adrees Latif

HOUSTON, Sept 2 (Reuters) - The city of Houston on Saturday witnessed two milestones on its road to recovery from Hurricane Harvey: a visit from the president of the United States and the return of baseball a week after deadly floodwaters engulfed the metropolis.

President Donald Trump, in a widely watched test of his handling of the disaster, distributed food and played with children at a center for evacuees in his first trip to Houston since it was slammed by one of the most destructive storms to hit the United States.

A few miles away, Major League Baseball returned to downtown Houston for the first time since Harvey came ashore last Friday as the most powerful hurricane to hit Texas in 50 years, bringing a welcome distraction to the fourth-most populous city, facing years of rebuilding.

In his second Texas visit since the storm struck, the president and his wife, Melania Trump, were greeted warmly on an unannounced stop to NRG center, a convention complex converted into a facility to assist storm evacuees.

"Really, I think people appreciate what has been done," Trump told reporters. "It has been done very efficiently, very well. There is a lot of love, a lot of love."

The visit gave Trump an opportunity to show an empathetic side to victims. Some have criticized him for staying clear of the disaster zone during a Texas visit on Tuesday, when he said he did not want to hamper rescue efforts.

The storm is expected to be one of the costliest natural disasters in U.S. history, displacing more than 1 million people and leaving behind wreckage in an area stretching more than 300 miles (480 kms).

Some areas of Texas received more than 50 inches (127 cm) of rain and the storm led to the deaths of at least 47 people.

The city of Houston ordered a mandatory evacuation for about 4,600 residences in the western part, where several hundred people have not left their homes.

"Put your own personal safety above your property," Mayor Sylvester Turner said, adding that residents should also consider the safety of first responders who would have to handle any emergencies.

The Trump administration on Friday asked Congress for a $7.85 billion appropriation for response and initial recovery efforts. Texas Governor Greg Abbott, who accompanied the Trumps, has said his state may need more than $125 billion.

The first couple's initial stop was at the center's "kid zone" where they hugged and chatted with some children playing there. At one point, Trump, dressed in a black rain jacket and no tie, picked up a child and kissed her on the cheek.

Later, the couple handed out prepared meals to the crowd, pausing frequently to greet and take "selfies" with aid recipients.

Kevin Hipolito, 37, an unemployed Houston resident rescued from the roof of his car two days earlier when his first-floor apartment was flooded, said he saw the Trump visit to the fourth-most populous U.S. city as a show of support.

"I'm a Democrat. It raises the morale," he said while the Trumps served lunch.

The Trumps later flew to flood-hit Lake Charles, Louisiana.

Harvey came on the 12th anniversary of Hurricane Katrina, which killed about 1,800 people around New Orleans. U.S. President George W. Bush's administration was roundly criticized for its botched early response to the storm, and the Trump administration appeared intent on avoiding such a misstep.

Late Saturday night, Trump tweeted "Just got back to the White House from the Great States of Texas and Louisiana, where things are going well. Such cooperation & coordination!"

Robert Hendricks, 48, an electrical engineer standing on line at NRG Stadium, was skeptical about Trump's visit helping.

"What's he going to do, use us as props to serve us lunch?" he said before adding: "It's good that he's showing his face."

PILES OF SOGGY DEBRIS

At Minute Maid Park, the Houston Astros opened a double-header against the New York Mets, the first time the team played at home since Harvey struck. Houston Mayor Sylvester Turner threw out the first pitch and a moment of silence was observed for those who died.

The Astros won the first game of the doubleheader 12-8.

The devastation from the unprecedented flooding to the Houston metropolitan area, with an economy as large as Argentina's, has been enormous. By Saturday, nearly 200,000 homes had suffered flood damage and about 12,600 were destroyed, according to the Texas Department of Public Safety.

Thirteen Texas Superfund sites, heavily contaminated former industrial zones, were flooded or damaged by Harvey, but the full impact on surrounding areas was not immediately clear, the U.S. Environmental Protection Agency said.

The announcement came amid rising concern about the health risks posed by Harvey's record floodwaters, which contain a toxic soup of chemicals, oil and bacteria from Houston's notoriously leaky sewer system.

For many people in the region, there was little time for baseball or the Trump visit as receding waters allowed them to return to flood-damaged homes for the first time since the Harvey came ashore on the Gulf Coast.

In a neighborhood in east Houston, streets were lined with 8-foot (2.4 meter) piles of soggy debris, including mattresses, carpets and other belongings ripped out of homes. Volunteers had set up shade tents with water and food and were helping residents remove the wreckage.

"It's overwhelming. It's sad to see it. We have a lot of good memories here," said Sergio Estrada who grew up in the neighborhood and came to help salvage the home where his parents live.

Many areas still were battling floodwaters from swollen rivers that were expected to last for a week or more. In Beaumont, about 85 miles (140 km) east, officials tried to repair a flood-damaged pumping station that caused the city of about 120,000 people to lose drinking water days ago.

To the east, flood-hit Orange County implemented a curfew from Saturday night to keep the community safe and give its residents "peace of mind," officials said.

The storm shut about a fourth of U.S. refinery capacity, much of which is clustered along the Gulf Coast, and caused gasoline prices to spike to a two-year high ahead of the long Labor Day holiday weekend.

Meanwhile a new storm, Irma, strengthened on Friday into a Category 3 hurricane on the five-step Saffir-Simpson scale.

It remained more than 1000 miles from the Leeward Islands, where residents were advised to monitor its progress. The National Hurricane Center said in an advisory late Saturday night it was still much too early to determine what direct impact it might have on the Bahamas and the continental United States.

(Additional reporting by Richard Valdmanis, Adrees Latif, Ernest Scheyder, Erwin Seba, Daniel Trotta and Catherine Ngai and Emily Flitter, Steve Holland in Washington, Julia Simon in New York and Jon Herskovitz in Austin, Texas, Writing by Jon Herskovitz and Frank McGurty; Editing by Bill Trott, Mary Milliken and Himani Sarkar)

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