Many of the businesses highlighted in 2017, like onX in Missoula, Bridger Aerospace in Bozeman, PFL in Livingston, and GTUIT in Billings, have continued a steep trajectory of job growth and investment.Experts at Next Frontier Capital, Frontier Angels, Montana Manufacturing Extension Center, Montana State University Blackstone LaunchPad, and University of Montana Blackstone LaunchPad helped us create this list of fast-growing companies to watch in 2018.