The 1992 Cable Act made exclusive franchises illegal, but does not retroactively apply to pre-1992 contracts. Almost all of those contracts have since expired and been renewed as non-exclusive contracts under the 1992 Act. Hazelton, for example, granted an exclusive franchise before 1992, which expired in 2005: http://articles.mcall.com/2004-03-25/business/3517245_1_fibe.... The suit in 2004 was over the last year of exclusivity.

I imagine there are some 30-year exclusive franchises granted in 1991 that are still in effect. I don't actually know of any.