He added, “Have a good time, everybody!”
Floodwaters are receding, and Mayor Sylvester Turner of Houston declared his city, the country’s fourth largest, “open for business.”
Still, many Houston streets remain four or more feet underwater after being pelted by 50 or more inches of rain over the past week.
On Saturday, The Associated Press reported that federal officials had yet to inspect highly toxic Superfund sites in the Houston area, several containing petrochemical residue, that were swamped and possibly leaking contaminants into surrounding areas.
An estimated 100,000 houses have been damaged or destroyed, with tens of thousands of displaced residents seeking shelter in local schools, in government buildings or on the couches of friends and neighbors lucky enough to live on higher ground.
The reaction inside the shelter to Mr. Trump’s visit was mostly positive, with a quieter undercurrent of anxiety and skepticism.
“Is he going to help? Can he help?” asked Devin Harris, 37, a construction worker. “I lost my home. My job is gone. My tools are gone. My car is gone. My life is gone. What is Trump going to do?”
Later, during a visit to First Church of Pearland, Mr. Trump loaded a few boxes full of supplies into pickup trucks and cars. Mr. Trump was equally enthusiastic in doling out credit there, praising local officials and offering a “what a job you’ve done” to the Federal Emergency Management Agency director, Brock Long, echoing the praise lavished by President George W. Bush on his FEMA director, Michael Brown, in the aftermath of Hurricane Katrina 12 years ago.
During his visit to Texas on Tuesday, the president met with emergency management officials in storm-brushed Corpus Christi and Austin, but he kept clear of nearby Rockport and other areas that bore the brunt of the storm, saying he did not want to interfere with early rescue and recovery efforts.
A few days later, by contrast, Vice President Mike Pence met with storm victims when he joined Gov. Greg Abbott of Texas in clearing fallen tree branches and other debris on the Gulf Coast.
On Saturday, Mr. Trump visited with families at the NRG Center, part of a complex that is home to the Houston Texans of the N.F.L. He chatted with parents and bent down to play with a few young children drawn to the president and his bustling entourage of Secret Service agents and camera-toting journalists.
“I’m a Democrat. It raises the morale,” said Kevin Jason Hipolito, 37, an unemployed Houston resident who was rescued from the roof of his flooded Acura after fleeing his swamped first-floor apartment.
“When he went to Corpus, I was like, ‘Man, he just forgot about us.’ This shows a lot of support,” Mr. Hipolito added.
A largely supportive crowd of about 100 people waving American flags and pro-Trump signs gathered outside Ellington Field Joint Reserve Base on Saturday morning to watch Air Force One land.
But not everyone thought that Mr. Trump should be making a visit — much less a second one — to an area still very much in disaster mode, where cities are still flooded, people are lining up for bottled water and homes are being evacuated.
“This has taken a lot of resources from the emergency medical workers,” said Connie Field, 62, a retired oil accounting worker from Sugar Land, Tex., who voted for Mr. Trump. “We still need them out there.”
Ms. Field, who waved a small American flag at passing military vehicles, did not suffer any damage in the flood. She praised the flood response from local officials, especially Houston’s mayor. She said Texas did not need Mr. Trump on the ground.
“Be at your command post,” she said. “The police need to be out watching these neighborhoods.”
White House officials, acutely conscious of such criticism, greenlighted Saturday’s trip after being given assurances by Texas officials that the visit would not disrupt recovery efforts, according to senior administration aides.
From Houston, Mr. Trump, accompanied by his wife, Melania Trump, and several cabinet members, was scheduled to fly to Lake Charles, La., where he was to meet briefly with emergency medical workers and members of the volunteer “Cajun Navy,” which helped rescue stranded residents in flood-ravaged neighborhoods.
From there he would return to Washington, where he was expected to spend the rest of Labor Day weekend monitoring developments in the Gulf.
The trip came hours after the administration submitted its initial hurricane recovery funding request to Congress, a $14.5 billion plan that is expected to be a down payment on a much bigger package that could exceed $100 billion, according to estimates by state and local officials.
Mr. Trump was traveling to two states newly free of the storm’s clutches but still suffering in its wake.
Flooding has knocked out the water systems of Beaumont, Tex., with a population of nearly 120,000, and local officials said they had no idea when service could be restored.
Late Friday, a chemical fire tore through a plant near Houston, sending a huge column of thick, black, noxious smoke into a sky finally clearing of clouds after days of rain.
Mr. Trump had to deal with the remnants of the storm personally as he arrived at Joint Base Andrews in Maryland to board Air Force One in a rainstorm. He exited Marine One, his helicopter, and was handed a large black umbrella, which he held over his wife’s head.
The president was wearing brown work boots. The first lady wore high heels, as she did during their flight to Texas on Tuesday. On the plane, she changed into a Texas baseball cap and azure-hued sneakers.
As Mr. Trump’s motorcade zipped past a church between the air base and the shelter, a Trump supporter flashed a placard reading, “Texans love stilettos.”