HOUSTON — Across the plains of West Texas, the pump jacks that resemble giant bobbing hammers define not just the landscape but the state itself: Texas has been built on the oil-and-gas business for the last 120 years, ever since the discovery of oil on Spindletop Hill near Beaumont in 1901.

Texas, the nation’s leading energy-producing state, seemed like the last place on Earth that could run out of energy.

Then last week, it did.

The crisis could be traced to that other defining Texas trait: independence, both from big government and from the rest of the country. The dominance of the energy industry and the “Republic of Texas” ethos became a devastating liability when energy stopped flowing to millions of Texans who shivered and struggled through a snowstorm that paralyzed much of the state.

Part of the responsibility for the near-collapse of the state’s electrical grid can be traced to the decision in 1999 to embark on the nation’s most extensive experiment in electrical deregulation, handing control of the state’s entire electricity delivery system to a market-based patchwork of private generators, transmission companies and energy retailers.