Mr. Bush’s prediction of lower-cost power generally came true, and the dream of a free-market electrical grid worked reasonably well most of the time, in large part because Texas had so much cheap natural gas as well as abundant wind to power renewable energy. But the newly deregulated system came with few safeguards and even fewer enforced rules.

With so many cost-conscious utilities competing for budget-shopping consumers, there was little financial incentive to invest in weather protection and maintenance. Wind turbines are not equipped with the de-icing equipment routinely installed in the colder climes of the Dakotas and power lines have little insulation. The possibility of more frequent cold-weather events was never built into infrastructure plans in a state where climate change remains an exotic, disputed concept.

“Deregulation was something akin to abolishing the speed limit on an interstate highway,” said Ed Hirs, an energy fellow at the University of Houston. “That opens up shortcuts that cause disasters.”