On November 29, 1948, before television viewership was widespread, "Roller Derby" debuted on New York television. The broadcasts increased spectator turnout for live matches. For the 1949–1950 season, Seltzer formed the National Roller Derby League (NRDL), comprising six teams. NRDL season playoffs sold out Madison Square Garden for a week. During the late 1950s and 1960s, the sport was broadcast on several networks, but attendance declined. Jerry Seltzer (Leo's son), the "Roller Derby" "commissioner", hoped to use television to expand the live spectator base. He adapted the sport for television by developing scripted story lines and rules designed to improve television appeal, but derby's popularity had declined.