Both Nebraska and Missouri claimed the 5,000 acre McKissick Island that extends almost two miles into Atchison County.

The most predominant denominations among residents in Atchison County who adhere to a religion are United Methodists (29.93%), Lutherans (LCMC) (22.16%), and Southern Baptists (14.33%).

Atchison County, along with the rest of the state of Missouri, is represented in the U.S. Senate by Josh Hawley (R-Columbia) and Eric Schmitt (R-Glendale).

Like most rural areas throughout northwest Missouri, voters in Atchison County generally adhere to socially and culturally conservative principles which tend to influence their Republican leanings.

On the Democratic side, former Vice President Joe Biden (D-Delaware) both won statewide and carried Atchison County by a wide margin.

Incumbent President Donald Trump (R-Florida) faced a primary challenge from former Massachusetts Governor Bill Weld, but won both Atchison County and statewide by large margins.

Businessman Donald Trump (R-New York) narrowly won the state overall and carried a plurality of the vote in Atchison County.

On the Democratic side, Senator Bernie Sanders (I-Vermont) carried Atchison County, but former Secretary of State Hillary Clinton (D-New York) won statewide by a small margin.

Senator Rick Santorum (R-Pennsylvania), who finished first in the state at large, but eventually lost the nomination to former Governor Mitt Romney (R-Massachusetts).

In 2008, the Missouri Republican Presidential Primary was closely contested, with Senator John McCain (R-Arizona) prevailing and eventually winning the nomination.

Then-Senator Hillary Clinton (D-New York) received more votes than any candidate from either party in Atchison County during the 2008 presidential primary.

Despite initial reports that Clinton had won Missouri, Barack Obama (D-Illinois), also a Senator at the time, narrowly defeated her statewide and later became that year's Democratic nominee, going on to win the presidency.