Clear Channel Outdoor is continuing to expand its digital billboard network, and has announced the next four markets in its ongoing rollout.

Four cities (Akron and Columbus, Ohio; Memphis, Tennessee; and Wichita, Kansas) have joined Clear Channel's six other cities with digital networks to host digital billboard networks of their own, according to the company, writes MediaBuyerPlanner.

Memphis has five 14 foot by 48 foot signs, while Akron has six. The networks in Wichita and Columbus consist of six 12 foot by 24 foot displays. All networks will rotate static advertising copy on each network display in an 8-second loop, totaling a minimum of 1,250 advertising spots each day.

Existing markets with Clear Channel Outdoor digital networks include Albuquerque, Cleveland, Las Vegas, Milwaukee, Minneapolis/St. Paul and Tampa.

Clear Channel's digital billboard network has run into snags in Minneapolis/St. Paul, with neighboring city Minnetonka refusing to power two such billboards in the metro area.