Obama also toured one of the worst-hit areas in the city.
The president spoke near the spot where Jeffrey Hunter was killed. The college senior, who was staying with his father and stepmother in Vilonia, while his mother was in Beebe 20 miles away sent her a last text message: "Goodbye Mama.... It's heading right for me."
The tornado that touched down April 27 was part of a deadly weather system that killed at least 35 people from Iowa to Mississippi and Alabama.
Obama talked of the contributions made by local residents who immediately pitched in, driving strangers to hospitals. One teenager did such an impressive job that "state troopers started taking orders from her," the president said.
"I could not be more impressed by the spirit of community that's here," Obama said.
Obama promised economic aid, saying he recognizes that Vilonia lost a lot of its sales-tax base along with buildings and infrastructure.
Sen. Mark Pryor, D-Ark., who invited Obama to visit Arkansas, and Gov. Mike Beebe accompanied the president on the helicopter ride from Little Rock. The visit was Obama's first to Arkansas as a sitting president and the first other than Bill Clinton, a former governor, to come to the state following a natural disaster since Herbert Hoover.