MISSOULA COUNTY, Mont.—A mountainous, 2,600-square-mile region with a population of approximately 119,600 does not seem like your prototypical setting for machine politics. Yet a recent audit of mail-in ballots cast there found irregularities characteristic of larger urban centers—on a level that could have easily swung local elections in 2020, and statewide elections in cycles past. The Biden administration, the Democrat-controlled Congress, and the Democratic National Committee are collectively pressing to both nationalize, and make permanent, many of the extraordinary pandemic-driven voting measures implemented during the 2020 election—particularly mass mail-in voting. Political leaders and prominent media outlets have dismissed concerns raised by critics that such measures invite voter fraud. But could the election in small-county Missoula call all that into question? The story at hand begins during the pandemic summer of 2020, when the then-governor, Democrat Steve Bullock, issued a directive permitting counties to conduct the general election fully by mail.  In the run-up to the election, a court …