Big Sky MX Challenge announces the return of motocross racing to the Gallatin County Fairgrounds Event Park. The Gallatin County Fairgrounds Event Park is set to host Round 3 of the 2015 Big Sky MX Challenge race series and will take place Saturday June 13 & Sunday June 14, 2015. The motocross event program will begin with a practice day open to the public, Saturday June 13, followed by a complete race day program, Sunday June 14. The premier racing classes, compete 12 PM to 3 PM on Sunday.