CenterPoint Energy Inc, the power company for most of the Houston area, still had about 767,000 customers in Texas without power, down from 2.15 million at the height of the storm.
CenterPoint predicted its team of 11,000 restoration workers would return power to most of the Houston area by September 25.
The company could not estimate when it will return service to homes and businesses along the Gulf Coast, including Galveston where the storm made landfall early on September 13.
Entergy Corp, the other hard-hit power provider in Texas, said 54,000 customers were still without power in eastern Texas, down from the 392,000 affected.
CenterPoint and Entergy Texas said Ike knocked out service to about 99 percent of their Texas customers.
Ike hit the Galveston-Houston area as a Category 2 storm with winds of 110 mph. Overall the storm cut power to more than 7.7 million homes and businesses in Arkansas, Illinois, Indiana, Ohio, Kentucky, Louisiana, Michigan, Missouri, New York, Ohio, Ontario, Pennsylvania, Texas and West Virginia as it marched from Texas to the Northeast from September 12-19.
CenterPoint, of Houston, transmits and distributes electricity to more than 2.1 million customers in Texas and natural gas to more than 3 million homes and businesses in Arkansas, Louisiana, Minnesota, Mississippi, Oklahoma and Texas.
Entergy, of New Orleans, owns and operates about 30,000 MW of generating capacity, markets energy commodities, and transmits and distributes power to 2.7 million customers in Arkansas, Louisiana, Mississippi and Texas.