Hmmmm... I seem to recall the Green Bay Slackers having a longer sellout streak than the Broncos. I believe their streak (unless it was broken in the past 5ish years) started in 1959.
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Looks like the Slackers streak fell during the 2016 playoff run. Making the Broncos the longest streak, which has been held <1 year.
http://www.foxsports.com/nfl/story/h...-giants-010517