Idaho 21st State Senate District, Idaho: Republican loyalist district. In 2024, voted R+10%. Republican peak: R+47 in 1904.
Key facts
- 2024 presidential margin
- R+10MIT Election Lab
- Political archetype
- Republican loyalistAkashic typology
- Population
- 10,2202024 5-year
- Median household income
- $91,5022024 5-year
- White (non-Hispanic)
- 83.1%2024 5-year
- Black
- 1.3%2024 5-year
- Hispanic / Latino
- 9.8%2024 5-year
- Peak Democratic margin
- D+28 in 1896MIT Election Lab
- Peak Republican margin
- R+47 in 1904MIT Election Lab
Constituent county margins for State Senate District 21, IDOne cell per constituent county, colored by 2024 presidential margin from deep red (Republican) through neutral to deep blue (Democratic), ordered bluest first.
R+60D+60
One cell per constituent county. Ordered by 2024 D-vs-R margin (bluest first). Hover for county-level numbers.
38 presidential elections
| Year | Won | Margin | Democratic | Republican | Total |
|---|---|---|---|---|---|
| R | 2,287 | 2,831 | 5,266 | ||
| R | 2,374 | 2,574 | 5,115 | ||
| R | 1,490 | 1,846 | 3,853 | ||
| R | 1,519 | 1,921 | 3,556 | ||
| R | 1,620 | 1,838 | 3,560 | ||
| R | 1,153 | 1,864 | 3,053 | ||
| R | 801 | 1,478 | 2,432 | ||
| R | 848 | 1,217 | 2,319 | ||
| R | 629 | 965 | 2,170 | ||
| R | 601 | 1,082 | 1,720 | ||
| R | 429 | 1,182 | 1,633 | ||
| R | 420 | 1,087 | 1,704 | ||
| R | 416 | 810 | 1,258 | ||
| R | 250 | 722 | 1,070 | ||
| R | 227 | 594 | 943 | ||
| R | 387 | 500 | 887 | ||
| R | 335 | 546 | 881 | ||
| R | 223 | 520 | 743 | ||
| R | 202 | 540 | 743 | ||
| R | 222 | 295 | 526 | ||
| R | 210 | 264 | 475 | ||
| R | 244 | 253 | 498 | ||
| D | 237 | 149 | 405 | ||
| D | 174 | 159 | 345 | ||
| R | 77 | 202 | 282 | ||
| R | 44 | 142 | 261 | ||
| R | 82 | 166 | 249 | ||
| R | 103 | 104 | 216 | ||
| O | 51 | 63 | 197 | ||
| R | 73 | 94 | 177 | ||
| R | 29 | 89 | 129 | ||
| R | 41 | 53 | 97 | ||
| D | 30 | 17 | 47 | ||
| O | 0 | 23 | 56 | ||
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Demographics
Race, ethnicity, and ancestry
Click any group to see the ancestries typically reported within it.
English
19.8%
German
18.0%
Irish
11.4%
American
4.3%
Italian
4.2%
Scottish
3.0%
French
2.3%
Source · American Community Survey 5-year estimates, 2024 release. Hispanic/Latino is an ethnicity that overlaps the race categories, so these shares can total more than 100%. Ancestry is a self-reported, multiple-response item; ancestry percentages do not sum to the parent race percentage.
Age distribution by sex
Median age: 38.4 in this county, 39.1 nationally
Male
Age
Female
85+
75–84
65–74
55–64
45–54
35–44
25–34
18–24
5–17
<5
Source · American Community Survey 5-year estimates, 2024 release.
Median household income
2024 inflation-adjusted dollars
$91,502
State Senate District 21 ranks near the middle of US counties.
State Senate District 21$91,502
Idaho$77,800
United States$80,734
Source · American Community Survey 5-year estimates, 2024 release.
Poverty rate
All persons below federal poverty line
8.3%
Child poverty is below the national average.
Children under 188.5%
Working age (18–64)8.3%
Seniors (65+)8.6%
Source · American Community Survey 5-year estimates, 2024 release.
Language at home
Population aged 5 and older
90.7%
speak English only
Spanish4.6%
Other Indo-European2.2%
Asian & Pacific Islander1.6%
Other languages1.0%
Source · ACS 5-year estimates, 2024.
Religious adherents
Adherents per capita by tradition
Source · 2020 US Religion Census. Remaining 52.5% of residents not counted as adherents by any reporting body.
With a 2024 presidential margin of R+65.6, this district of roughly 53,000 residents ranks among the most uniformly partisan constituencies in the state, leaving general-election competition essentially absent at every level.
The Republican margin in Idaho 21st State Senate District reached its widest at forty-seven points in 1904. The margin in 2024 was ten points, in line with the district's deep historical pattern.
Its loyalty is rooted in its place. Median household income of $91,502, a 83% non-Hispanic-white share, and a population of 10,220 together describe a district whose political habits are deeply settled.
Compare two places, side by side
Twelve curated comparisons line up election history, demographics, and the divergence story for two places at a glance. Browse all comparisons →
Cite this page
All citations released under CC BY 4.0. Attribution: Akashic Intelligence.
State Senate District 21, Idaho. Akashic. https://akashic.app/sld-upper/16021/. Accessed May 20, 2026. License: CC BY 4.0.
License: CC BY 4.0
Frequently asked questions
How did State Senate District 21, Idaho vote in 2024?
In 2024, State Senate District 21, Idaho voted Republican by 10.3 points (R+10), carried by the Republican candidate. Out of 5,266 votes cast, 2,287 went Democratic and 2,831 went Republican.
What is State Senate District 21, Idaho's political archetype?
Akashic classifies State Senate District 21, Idaho as a "Republican loyalist" district based on its long-arc presidential voting pattern. Across 38 elections in the dataset, the district has voted Democratic 3 times, Republican 29 times, and other 2 times.
When did State Senate District 21, Idaho last vote Democratic?
The most recent presidential election in which State Senate District 21, Idaho voted Democratic was 1936.
How many people live in State Senate District 21, Idaho?
State Senate District 21, Idaho has a population of 10,220 according to the 2024 American Community Survey 5-year estimates from the US Census Bureau.
What is the median household income in State Senate District 21, Idaho?
Median household income in State Senate District 21, Idaho is $91,502 — above the national median of $80,734. The Idaho state median is $77,800.
What is the political history of State Senate District 21, Idaho?
Akashic tracks 38 presidential elections in State Senate District 21, Idaho from 1876 to 2024. Of those, 3 went Democratic and 29 went Republican. The district's archetype — "Republican loyalist" — captures the overall trajectory of that voting record.