The sprawling remains of Hurricane Alex has drenched much of northern Mexico, paralysing the major city of Monterrey.
At least two people were killed when the dry river roared to life and roads turned into rushing streams.
Hurricane Alex ripped off roofs, caused severe flooding and forced thousands of people to flee coastal fishing villages as it hit land Wednesday evening in the border state of Tamaulipas. Power and telephone service were down in several towns and cities.
The storm weakened to a tropical storm today as it moved west to Nuevo Leon state, but still caused major disruptions.
One man died when he was swept away by a torrent of water along a six-lane highway, city Civil Protection director Pedro Trevino told Televisa Monterrey network.
Another man was founded drowned by side of a creek.
Nuevo Leon state governor Rodrigo Medina de la Cruz told the Televisa network he had ordered all schools closed and appealed for people to stay home from all but essential jobs.
The US Consulate in Monterrey also closed due to the storm.
Mr de la Cruz said Alex had already dumped 16 inches of rain in some areas.
Schools were also cancelled in Tamaulipas state, where clean-up efforts began and flood waters started subsiding.
Crews swept up debris in Matamoros, a city across the border from Brownsville, Texas. Emergency officials still had to use boats to survey the damage in some neighbourhoods.
Most of the 2,500 people who stayed in shelters overnight boarded buses back to their coastal villages today after lining up for breakfast served by marines.
"The city is practically under water," said Saul Hernandez Bautista. "But the most important thing is that there was no loss of life. We took important and opportune measures to evacuate people."
Raging winds knocked down hundreds of trees, telephone posts and traffic lights in the Matamoros area and further south along Mexico's northern Gulf coast.
Power and telephone services were out in San Fernando, a town near where Alex made landfall, and in the state capital of Ciudad Victoria.
Abel Ramirez, of San Fernando's Civil Protection and Fire Department, said seven fishing villages with a combined population of about 5,000 people were evacuated.
But there were no reports of injuries. "We're better," Mr Ramirez said as he surveyed the damage.
The Atlantic season's first hurricane largely spared nearby Texas, which had prepared for a possible direct hit.
While it brought rain, spawned two tornadoes and caused 1,000 people to evacuate low-lying areas there, state officials reported no injuries or major damage.
Pumps sucked out high water in only a few remaining flooded areas in Texas by this morning. Authorities said low-lying colonias - unincorporated communities frequently without public utilities - stood up well to Alex.
"It was a great drill," said Johnny Cavanos, Cameron County's emergency management co-ordinator.
More than 1,000 people who packed shelters in Hidalgo and Cameron nearly all left to return home at daybreak.
American Electrical Power reported that fewer than 2% of customers were without power, a mere blip compared with the 211,000 homes blacked out when Hurricane Dolly thundered ashore two years ago.
Alex was the first June hurricane in the Atlantic since 1995, according to the hurricane centre.
Earlier, Alex whipped up high waves that frustrated oil spill clean-up efforts on the other side of the Gulf of Mexico and delivered tar balls and blobs of crude oil on to already soiled beaches.