Crowd size is mostly irrelevant
An emerging storyline in the last few weeks has been the sizable crowds that have shown up to hear from Sanders. In Minneapolis, over 3,000 people listened to Sanders at a mass meeting; in Denver, almost 5,000 people; in Madison, WI, nearly 10,000; and, most recently, around 8,000 in Portland, ME.
However, its important to remember that crowd size fundamentally doesnt matter much. Comparisons between how large one candidates crowd is compared to anothers are ripe for misunderstanding. Just think back to 2012, when press reports and GOP partisans frequently mentioned the large numbers that Mitt Romney was drawing on the campaign trail. Did this end up mattering? Obama won the popular vote by about 5 million votes. The history of crowdsmanship is long, and as Louisiana politico Robert Mann noted back in 2012, full of anecdotal evidence that wound up meaning nothing.
Consider the demographics of Denver, Madison, Minneapolis, and Portland: Of those four, only the Mile High City is less than 60% white (53%), and of the 50 biggest cities in the United States, Denver and Minneapolis are among the 18 that are majority non-Hispanic white. Portland is the biggest city in Maine, over 80% white, and located in the Pine Tree States most liberal area, Cumberland County. Madison is three-fourths white and an über-liberal university city its no surprise so many people showed up to see Sanders there. In fact, many college towns are going to be among the most receptive to Sanders campaign message. Take Charlottesville, VA, for example. One of the Crystal Balls writers tried to scout out Sanders when he came to the home of the University of Virginia in May, but the venue only held about 200-300 people and was packed to fire-code capacity by the time he arrived at the front of a long line. Nonetheless, Sanders smartly engaged the many who couldnt get inside with an impromptu talk.
Sanders support in places such as Madison and Charlottesville is indicative of where his principal backing is drawn. National surveys and polls in Iowa and New Hampshire all show him performing noticeably stronger among more left-leaning voters than more moderate ones. At the same time, Clinton seems to be running fairly equally among liberal and moderate Democrats, an indicator of her broad support within the party, even with Sanders recent rise. Just as only a few Republicans seem to have the multi-factional appeal to truly compete for their partys nomination, Clinton is in a similar position when it comes to Democratic voters.
At the end of the day, the crowd sizes dont indicate that Sanders will win far from it but the one takeaway from them is that the left wing of the Democratic Party wants to entertain the idea of a Clinton-less future, and Sanders is the candidate who has received the lefts energy at this point. As he is to the left of the other Democratic candidates not named Clinton, hes become a natural focal point for frustration with Clintons ties to Wall Street, her center-left outlook, and her foreign policy past (e.g., her Iraq War vote).