[2] Henry County is included in the Davenport-Moline-Rock Island, IA-IL Metropolitan Statistical Area.

The New England settlers founded the five towns of Andover, Wethersfield, Geneseo, Morristown and La Grange.

The area is fairly flat, with elevations ranging from 650 feet above sea level in the northwest to 850 in the southeast.

After being largely Democratic in its first few elections, the county turned powerfully Republican for the 110 years following the formation of that party.

The only time it did not vote Republican between 1856 and 1960 was in 1912 when the GOP was mortally divided and Progressive Theodore Roosevelt won a majority of the county's ballots.

In the 1980s, the transition of the Republican Party into a party largely based around Southern Evangelicals severely alienated its historic Yankee base: Henry County turned to Democrat Michael Dukakis in 1988, and voted Democratic in every election between 1988 and 2012 except that of 2004 when George W. Bush carried the county by 5.1 percent.

In 2020, Trump built on his win in 2016, capturing 60% of the vote - the highest Republican percentage in 40 years.