Dean Ambrose (United States Champion) – 351 days
Although the longest-reigning champion with the United States Title is often criticized for defending it on the least occasions, WWE still considers this run, legit in the modern era. The Lunatic fringe pinned Kofi Kingston at Extreme Rules 2013 to win the belt and his Shield brethren protected him to hold the gold for almost a year until he lost it to Sheamus in 2014.