started using Riverside Church for services, drawing 2,000 attendees on average, and continued to hold its services at the church until October 1945. In June 1945, Fosdick announced he would step down as senior minister the following May. This spurred a search for a new pastor and in March 1946, Robert James McCracken was chosen for the position and officially became the senior pastor of Riverside Church that October. Fosdick and McCracken held each other in mutual respect so the transition between ministers went smoothly. Over the next two decades, McCracken continued Fosdick's policy of religious liberalism. In 1956, halfway through McCracken's tenure, the church conducted an internal report and found the organizational structure was disorganized and that most staff did not feel any single person was in charge. As a result, six councils were created and placed under the purview of the deacons and trustees. The councils partitioned power into "a series of mini-kingdoms", according to a later pastor, Ernest T. Campbell. Construction on the Martin Luther King Jr. Wing, to the south of the existing church, started in 1955. The seven-story wing was designed by Collens, Willis & Beckonert, successors to Allen & Collens; its $15 million cost was funded by Rockefeller. The wing was dedicated in December 1959 and contained additional facilities for the church's programs. A dummy antenna had been placed on top of Riverside Church's -tall carillon earlier that year to determine whether it could be used by Columbia University's radio station, WKCR (89.9 MHz FM), despite strong opposition from parishioners and the local community. Nevertheless, the church decided to place an antenna atop the carillon for its own radio station, the top of the antenna being above ground level. Riverside Church started operating the radio station WRVR (106.7 MHz FM) in 1961 and continued to operate it until 1976. In 1960, Riverside Church's congregation voted to join the United Church of Christ, the successor denomination to the Congregational Christian Churches. Rockefeller purchased the Stone Gym, an existing Union Theological Seminary building southeast of the original church, and reopened it as a community facility in April 1962 after a five-year renovation. In April 1967, McCracken announced he would leave his position as senior minister, citing health issues. Late 1960s through 1990s Ernest T. Campbell became pastor in November 1968. Less than a year later, civil rights leader James Forman interrupted a sermon at Riverside Church,