USA is keeping "The 4400" earthbound for another year.

The cable network has picked up a fourth season of its sci-fi drama about 4,400 people who disappeared over the years and have returned to Earth just as they were when they left -- aside from the extraordinary powers many of them possess. The show wraps up its third season on Sunday.

"This show continues to thrive creatively from year to year," says Jeff Wachtel, who oversees original programming at USA. "We're looking forward to another season filled with intriguing characters, unique twists and incredibly suspenseful storylines."

Ratings for the show this season haven't approached the heights of previous years, but "The 4400" still regularly draws better than 3 million viewers per week, enough for USA to deem it a "ratings powerhouse." It also attracted some additional buzz recently with the return of Billy Campbell's presumed-dead character, Jordan Collier.

Production on season four is scheduled to begin in early 2007, with the premiere set for next summer.