The slow-churning remnants of Tropical Storm Imelda have left at least four people dead in Texas, with rescue crews in boats scrambling to reach stranded drivers and families trapped in their homes.
By Thursday night, floodwaters had started receding in most of the Houston area, said mayor Sylvester Turner, after a relentless downpour that drew comparisons to Hurricane Harvey two years ago.
Police were working well into the night to clear roads of vehicles stalled and abandoned because of flooding, Houston Police Chief Art Acevedo said.
The storm also flooded parts of south-western Louisiana.
More than 900 flights were cancelled or delayed in Houston.
A 19-year-old man drowned and was electrocuted while trying to move his horse to safety, according to a message from his family shared by Jefferson County Sheriff’s Office. Crystal Holmes, a spokeswoman for the department, said the death occurred during a lightning storm.
A man in his 40s or 50s drowned when he tried to drive a van through 8ft water near Bush Intercontinental Airport in Houston during the Thursday afternoon rush hour, Harris County Sheriff Ed Gonzalez said.
The National Weather Service said preliminary estimates suggested Jefferson County was deluged with more than 40in of rain in 72 hours, which would make it the seventh wettest tropical cyclone in US history.
Even when Houston was finally rid of the worst, central roads remained littered with abandoned cars submerged in water. Thousands of other drivers were at a practical standstill on narrowed lanes near flooded banks.
Mr Turner evoked the memory of Harvey – which dumped more than 50in of rain on the nation’s fourth-largest city in 2017 — while pleading with residents to stay put.
Ahead of the evening rush hour, Houston officials urged commuters to stay in their offices for an extra three to four hours rather than embark on flooded and already jammed roads.
Mr Turner made a similar appeal to parents as Houston Independent School District — Texas’s largest with more than 200,000 students — did not cancel classes or shorten the day, unlike neighbouring districts in the path of the storm. The district cancelled Friday classes.