Turns out Prohibition has lost a bit of its appeal in America. The Roaring ’20s-based Boardwalk Empire returned to HBO last night at 9 PM for its fourth season with 2.4 million viewers. That’s down from the 2.9 million who watched the Season 3 opener on September 16, 2012 at 9 PM. Of course, last year’s Boardwalk Empire season debut didn’t have to face the NFL and NBC’s first Sunday Night Football game as last night’s premiere did. With the 11 PM replay airing added, Boardwalk Empire had a total viewership of 3.2 million last night. Over three same night airings, the Season 3 premiere pulled in 4.6 million viewers. The 9 PM broadcast of the Season 3 opener last year was on par with Season 2’s September 25, 2011 premiere. Last night’s Season 4 debut was also down from the 2.7 million who watched the 9 PM broadcast of the Season 3 finale on December 2, 2012. The Season 3 ender was down from the 3 million who watched the first airing of Boardwalk’s Season 2 finale on December 10, 2011. Taking place in the winter of 1924, Sunday’s premiere saw Steve Buscemi’s Nucky Thompson make peace with his underworld rivals, a new club open in Atlantic City, a very messy death and Ron Livingston make his debut as a series regular.