County record · fips 17131 · Illinois
MercerIL
Republican ×3 since 2016all 40 elections, 1868–2024
The Long Record
40 elections against the Illinois and national vote
2024 result
R+27.7
won by Republicans
Record since first cycle
9–31
Dem–Rep two-party wins
Voted with the winner
26/40
65% of its elections
Closest election
2004
D+1.2
this countyIllinoisnational (official)dot colour = two-party winner · hollow = tie or unknown total · click a dot to open that election
The Biggest Swings
Cycle-over-cycle change in the two-party margin, in points
| Election | Swing | Toward |
|---|---|---|
| 1872 | -72.4 pts | Republicans |
| 1876 | +70.9 pts | Democrats |
| 1912 | +48.6 pts | Democrats |
| 1916 | -46.6 pts | Republicans |
| 1932 | +40.7 pts | Democrats |
Who Lives Here
Census & ACS county profile, 2024
Population
15,495
College (BA+)
21%
Median income
$74,182
2024 dollars
Non-white
7%
Rural
100%
Age 65+
22%
Interpolated between Census/ACS anchors; income CPI-deflated to 2024. Demographics begin in 2000 — earlier cycles have returns only.
Neighbouring counties
Henderson, IL · Henry, IL · Knox, IL · Rock Island, IL · Warren, IL · Des Moines, IA · Louisa, IA