Until the broadcast, an openly gay person had never anchored the nightly news on network TV. Roberts told The Advocate that it was a "huge honor" to fill the role.
During the week, Roberts hosts "MSNBC Live With Thomas Roberts."
There are a few openly gay evening news anchors on cable TV -- MSNBC's Rachel Maddow, CNN's Anderson Cooper and Don Lemon -- but Roberts is the first for one of the big three networks.
Watch the historic broadcast