The single county to watch in Montana's special election

Lake County has a history of accuracy in matching statewide election results.

— -- If you’re only watching one county in Thursday’s special election for Montana's lone U.S. House seat, it should be Lake County.

Wrapping around the base of Flathead Lake in rural northwest Montana, the county includes just three cities and towns, in addition to the Flathead Indian reservation and other rural areas. But this unassuming rural Montana area has had nearly perfect accuracy in predicting Montana's federal and gubernatorial statewide elections over the past two decades.

Republican multi-millionaire tech executive Greg Gianforte is slated to face off against Democratic populist singer-songwriter Rob Quist in this GOP-leaning U.S. House district on Thursday, after the seat was vacated by now-Interior Secretary Ryan Zinke.

But in November, Lake County pinpointed both candidates' support in both races within one percentage point. In fact, only once since 1996 has the county failed to vote with the winner of the statewide vote, according to an ABC News analysis of data from The Associated Press and the Montana Secretary of State.

Compare for yourself: Here's a look at each race over the last two decades.

Not only has Lake County called the correct winner with a shocking degree of accuracy; it's also precisely matched the support of each candidate in such statewide races.

Lake County has matched both major party candidates' statewide result within 2 percentage points or less in 22 of the last 26 federal and gubernatorial elections. It’s also predicted the statewide margin within an average of 2.5 percentage points since 2002 -- and a razor-thin 1.2 points in the last five such statewide races.

Lake County, Montana has matched federal and gubernatorial race margins within an average of 2.5 points since 2002. https://t.co/Pspt2JecRY pic.twitter.com/fE12qeQ8Iv

— Ryan Struyk (@ryanstruyk) May 24, 2017

So what makes Lake County such a predictive swing county in Montana? It's home to fewer than 30,000 people in only three census-designated cities or towns.

Other small areas in the southern part of the county with large American Indian populations -- like St. Ignatius and Ronan -- also went for Bullock in the gubernatorial race in November. The eastern side of Polson -- the major city in Lake County located on the southern tip of Flathead Lake -- also went narrowly for Bullock.

But rural areas in the northern part of the county vote overwhelmingly for Republican candidates. One rural precinct near Swan Lake voted for Trump by almost 60 percentage points. Other strong GOP areas that voted for Gianforte in the gubernatorial race by double digits include Dayton, Ferndale and the western side of Polson.

Here's a look at the county's geography:

And if there's one precinct to watch, it's the eastern side of downtown in the county's largest city: Polson. The 5th precinct nearly exactly matched both the Lake County and the Montana statewide margins in these two races. Trump won the precinct by 19 percentage points and Bollock won it by a single percentage point. Its eastern neighbor, the 7th precinct of Polson, is another one to watch.

The county also splits its representation in the state legislature among five Republicans and three Democrats, according to the county's website.

Lake County, Montana has matched federal and gubernatorial race margins within an average of 2.5 points since 2002. https://t.co/Pspt2JecRY pic.twitter.com/fE12qeQ8Iv

So what makes Lake County such a predictive swing county in Montana? It's home to fewer than 30,000 people in only three census-designated cities or towns.

Other small areas in the southern part of the county with large American Indian populations -- like St. Ignatius and Ronan -- also went for Bullock in the gubernatorial race in November. The eastern side of Polson -- the major city in Lake County located on the southern tip of Flathead Lake -- also went narrowly for Bullock.

But rural areas in the northern part of the county vote overwhelmingly for Republican candidates. One rural precinct near Swan Lake voted for Trump by almost 60 percentage points. Other strong GOP areas that voted for Gianforte in the gubernatorial race by double digits include Dayton, Ferndale and the western side of Polson.

Here's a look at the county's geography:

And if there's one precinct to watch, it's the eastern side of downtown in the county's largest city: Polson. The 5th precinct nearly exactly matched both the Lake County and the Montana statewide margins in these two races. Trump won the precinct by 19 percentage points and Bollock won it by a single percentage point. Its eastern neighbor, the 7th precinct of Polson, is another one to watch.

The county also splits its representation in the state legislature among five Republicans and three Democrats, according to the county's website.

Top Stories

Top Stories

Top Stories

Top Stories

ABC News Live

ABC News Live

24/7 coverage of breaking news and live events