It's a very good question given that, when it comes to old-time music, it is often hard to tell. This music is inspired by the string bands of the '20s and '30s, and those within it tend to stay very close to the tradition, playing the songs just as they've been played for decades. The Freight Hoppers are no strangers to that kind of maintenance, and their past recordings and performances have largely curated the traditional songbook.
Because it is such a conservative form, it's easy to raise the ire of other players who want nothing at all to change. The Freight Hoppers, in their way, are shaking things up. They have written new material, and therefore are bringing some new ideas and new sensibilities to the musical form. They are also clearly having a lot of fun, and that's perhaps the most important part.
The typical themes from Depression-era America are all here: common sense wisdom, moralism and the trouble with finding work, food and just making it through the day in one piece. But the air of celebration is here as well. They're not interested in musicology, and they don't think we should be either. The Freight Hoppers remind us that, no matter what our particular worries might be, sometimes you've just got to get out there and dance.