One of the predecessors of The CW, The WB Television Network had maintained a similar group of subscription-only affiliate stations in small- and select medium-sized markets called The WB 100+ Station Group, which began operations on September 21, 1998 and continued to operate until The WB ended operations on September 17, 2006. On February 24, 2006, one month after CBS Corporation and Time Warner announced the launch of the new network, The CW formally released a proposal to prospective affiliates announcing the creation of The CW Plus, a similar single-network feed for smaller markets – covering the same areas that were served by The WB 100+. While there was no guarantee that existing affiliates of The WB 100+ would automatically join The CW Plus, most of them (particularly cable-only affiliates) ultimately did join the new service, and programming transitioned seamlessly from The WB 100+ to The CW Plus.