Overland Park, Kan.-based Sprint said it would gain 585,000 customers and spectrum that can be used to build out its high-speed long-term evolution wireless network. The company, which last month agreed to sell a controlling stake to Japan's Softbank Corp. for $20 billion, also has a deal in place with Eagle River Holdings LLC that would give it control over wireless Internet service provider Clearwire Corp.

Sprint CEO Dan Hesse in a statement said the deal for U.S. Cellular's operations "will enable us to strengthen our business and become a more robust competitor."

The company, the nation's third-largest wireless provider, is attempting to build out its network to better compete against titans AT&T Inc. and Verizon Communications Inc.

"Acquiring this spectrum will significantly increase Sprint's network capacity and improve the customer experience in several important Midwest markets including Chicago and St. Louis," Hesse said.

U.S. Cellular in a message to customers on its website said that in the markets it is selling "we aren't reaching the rate of profitable customer growth we need to justify continuing to make investments and continue our operations."

The markets to be sold generated revenue of about $340 million in the nine months ended Sept. 30, 11% of total sales, and operated at a loss.

"Exiting these markets enables us to play to our strengths in markets where we have higher penetration and where we can effectively sharpen our proven strategy to differentiate the U.S. Cellular customer experience from other wireless carriers," company CEO Mary N. Dillon said in a statement.

Post-deal, U.S. Cellular would still have more than 5.2 million customers spread across New England, the mid-Atlantic, Pacific Northwest and Midwest.

Wells Fargo Securities LLC senior analyst Jennifer M. Fritzsche in a note called the deal "a logical move" for Sprint and "an intriguing" one for U.S. Cellular. The seller, according to Fritzsche, "appears to be placing its focus on the rural markets where it is apparently much more profitable due to the higher penetration it has as well as the roaming revenue it generates from other carriers."

Stifel Nicolaus Weisel analyst Christopher C. King said it was unclear what U.S. Cellular would do with the proceeds, saying "its options are somewhat limited outside of returning cash to shareholders."

Falkenberg Capital Corp. represented U.S. Cellular on the deal.

-- Chris Nolter contributed to this report.