Some bands simply evolve more than others. Over six years and three albums, The Mighty Short Bus has come barreling out of Madison, touring the Midwest as one of the city’s hardest-working DIY groups while consistently redefining its sound.

The Forever Endeavor bears little resemblance to 2006’s Rogue Nation, a raucous record that didn’t sound like The Mighty Short Bus’ sunny 2004 debut, When the Time Comes. Rather, this organic, rootsy collection of songs reveals a band that has finally found its soul. Dual singers-songwriters-guitarists Frank Busch and Nic Adamany invoke a younger Kurt Neumann and Sam Llanas with their summertime harmonies on “Go On, Go On,” “Out West” and “Fool’s Gold.” “Don’t Mess With Texas” and “Minnesota” tell engaging stories, and “Ol’ #7” displays Busch’s flair for country.

The Mighty Short Bus can still cover The Black Crowes and Tom Petty better than most above-average bar bands, but The Forever Endeavor should garner this quartet deserved attention on its own.