MS NOW

Why the Pennsylvania primary stands out as unique

Voters will go to the polls today in five states, but one contest in particular stands out — and not just because it's the biggest.

An Amtrak train travels northbound from 30th Street Station, May 18, 2015 in Philadelphia. (Photo by Matt Slocum/AP)
An Amtrak train travels northbound from 30th Street Station, May 18, 2015 in Philadelphia.AP

Steve Benen is a producer for "The Rachel Maddow Show," the editor of MaddowBlog and an MS NOW political contributor. He's also the bestselling author of "Ministry of Truth: Democracy, Reality, and the Republicans' War on the Recent Past."