You might have heard that Texas has its own power grid. Did you know not all parts of the state use it?

While millions of Texans were left in the dark this week after an arctic blast pummeled the state, not every part of Texas experienced major electricity issues.

Texas has an unusual power setup. Unlike the other states in the union, which are mostly interconnected, Texas has its own power grid. That grid, which operates as the Electric Reliability Council of Texas, covers 90% of the state. The other 10% includes El Paso, the upper Panhandle and a chunk of East Texas.

These areas, for various reasons, including proximity, instead get their electricity from other grid providers. For example, the Panhandle is closer to Kansas than to Dallas.

The main culprit for the power outages in ERCOT’s coverage area was failures across Texas’ natural gas operations and supply chains due to the extreme temperatures. From frozen natural gas wells to frozen wind turbines, all power sources faced difficulties during the winter storm. Texans largely rely on natural gas for power and heat generation, especially during peak usage, experts said.

Energy and policy experts told The Texas Tribune this week that limited regulations on companies that generate power and a history of isolating Texas from federal oversight help explain the crisis. They said Texas’ decisions not to require equipment upgrades to withstand extreme winter temperatures and to operate mostly isolated from other grids in the U.S. left the power system unprepared for this week’s outages.

But the weather didn’t plunge other parts of the state into darkness. Their grids were equipped to withstand those frigid temperatures.

Take El Paso, for instance. El Paso’s power was originally all local, but it started looking for other resources in the 1960s as the population grew, including turning to a New Mexico power plant. Then in the late 1970s, El Paso Electric became part owner of the Palo Verde Nuclear Generating Station in Arizona.

“You look where El Paso is, and people not from this area don’t understand. I can get from Los Angeles faster than I can get to Houston,” said Steven T. Buraczyk, senior vice president of operations for El Paso Electric. “Economically it just made more sense for us to be part of the Western grid because of where we’re located.”

El Paso also has access to the Montana Power Station, built on the east side of town after the hard freeze in 2011 that left the city without power and water. Buraczyk said officials made several critical decisions after that storm to prevent a similar situation from happening in the future, including having its equipment being able to withstand low temperatures as low as negative 10 degrees.

“We went back and did some better insulation and weatherization to withstand colder temperatures,” said Buraczyk. “But the biggest thing, in my mind, is we built another power plant. It’s difficult to retrofit something that is 50 or 60 years old. And have as good results as when you’re just building it.”

Earlier this week, El Paso Electric spokesperson Eddie Gutierrez told El Paso TV station KTSM that “only 875 customers were impacted by an outage of less than five minutes” because they were better prepared this time around.

The Panhandle also escaped major damage this week. Residents there have dealt with short, rolling blackouts but nothing like the dayslong outages in the other parts of the state, reports Amarillo TV station KAMR. Most of the Texas Panhandle and South Plains get their power from Xcel Energy, serviced by the Southwest Power Pool. That power grid spans 14 states, which allows them to share power when there’s a need. The region SPP serves also experienced harsh weather conditions this week, which is why the Panhandle experience some power outages.

Xcel Energy spokesperson Wes Reeves told KAMR the company has spent time and effort weatherizing its power plants in the last decade.

The Beaumont area is serviced by Entergy, which also beefed up its weatherization efforts before the storm. That allowed them to have fewer long-term outages compared with other parts of the state, Houston’s KHOU-TV reports.

Beaumont residents still experienced rolling outages after its power grid, Midcontinent Independent System Operator, became overwhelmed by the all-time high demand for electricity. At one point this week, about 33,000 residents experienced these outages. On Thursday, Entergy said it hoped to restore power to its customers by the end of the day.

Disclosure: El Paso Electric Co. and Entergy have been financial supporters of The Texas Tribune, a nonprofit, nonpartisan news organization that is funded in part by donations from members, foundations and corporate sponsors. Financial supporters play no role in the Tribune's journalism. Find a complete list of them here.