It keeps getting deeper for Houston, the epicenter of the U.S. oil industry.

As floods inundated the nation’s fourth-largest city Monday, with an estimated 20 inches of rain still to come, predictions of damage ranged as high as $100 billion. Wall Street and Washington braced for the repercussions of the costliest U.S. natural disaster since Hurricane Sandy in 2012.

Tropical Storm Harvey, which made landfall as a category 4 hurricane, drifted into the Gulf of Mexico, poised to recharge before crashing ashore again Wednesday on the Texas-Louisiana border. As much as 30 percent of the nation’s refining power was imperiled, according to analysts at Tudor Pickering Holt & Co.

Houston was born from the wreckage of a cataclysmic storm in 1900, and in the decades since has weathered not only water and wind but the gyrating fortunes of the oil industry. The sprawling megalopolis, which takes a perverse pride in