akashic
1876–2024
State Senate District 18·Idaho

Idaho 18th State Senate District has voted Republican in twenty-two straight presidential cycles.

Boise's urban core tilts sharply Democratic in statewide races

1876 — 2024·38 elections
ID
Latest
R+10
in 2024
Archetype
Republican loyalist
since the recent cycles
Population
70,027
2024 ACS

Idaho 18th 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
70,0272024 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
2024 results by constituent county
1 counties · 0 D · 1 R
R+60
D+60
One cell per constituent county. Ordered by 2024 D-vs-R margin (bluest first). Hover for county-level numbers.
38 presidential elections
Source · MIT Election Lab · ICPSR · VEST (precinct-level 2024).
YearWonMarginDemocraticRepublicanTotal
R
−10.3%
15,66919,39936,086
R
−3.9%
16,26617,63735,045
R
−9.2%
10,21212,65126,399
R
−11.3%
10,40913,16424,364
R
−6.1%
11,09712,59424,392
R
−23.3%
7,89712,77120,920
R
−27.9%
5,48510,12816,664
R
−15.9%
5,8088,34115,889
R
−15.5%
4,3106,61214,866
R
−28.0%
4,1197,41511,785
R
−46.2%
2,9368,10111,190
R
−39.1%
2,8787,45011,679
R
−31.3%
2,8515,5518,621
R
−44.2%
1,7124,9487,329
R
−39.0%
1,5564,0736,461
R
−12.8%
2,6503,4286,078
R
−23.9%
2,2963,7386,035
R
−39.9%
1,5293,5615,089
R
−45.4%
1,3873,6995,092
R
−13.9%
1,5192,0203,604
R
−11.4%
1,4391,8103,258
R
−1.9%
1,6711,7363,413
D
+21.6%
1,6231,0232,776
D
+4.4%
1,1921,0872,364
R
−44.4%
5291,3871,931
R
−37.5%
3049741,789
R
−33.6%
5631,1361,703
R
−0.8%
7037151,480
O
−6.3%
3474321,349
R
−11.8%
5026451,215
R
−47.0%
198612881
R
−12.8%
280365665
D
+28.3%
207115325
O
−41.5%
0158381
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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
0.6%
85+
1.0%
2.3%
75–84
2.6%
4.7%
65–74
5.2%
5.8%
55–64
6.0%
6.6%
45–54
6.2%
7.4%
35–44
7.1%
7.2%
25–34
6.7%
4.6%
18–24
4.3%
8.7%
5–17
8.2%
2.6%
<5
2.5%
Source · American Community Survey 5-year estimates, 2024 release.
Median household income
2024 inflation-adjusted dollars
$91,502
State Senate District 18 ranks near the middle of US counties.
State Senate District 18$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
Other Christian
23.7%
Catholic & Orthodox
13.8%
Methodist
3.7%
Pentecostal & Holiness
2.5%
Mainline Protestant
1.8%
Non-Christian
1.0%
Baptist
1.0%
Source · 2020 US Religion Census. Remaining 52.5% of residents not counted as adherents by any reporting body.

Idaho Senate District 18 covers a dense slice of Ada County where the 2024 presidential margin reached D+22.8 — an outlier in a state that leans heavily Republican statewide, reflecting the district's younger, college-educated urban electorate.

The Republican margin in Idaho 18th 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 70,027 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 18, Idaho. Akashic. https://akashic.app/sld-upper/16018/. Accessed May 20, 2026. License: CC BY 4.0.
License: CC BY 4.0

Frequently asked questions

How did State Senate District 18, Idaho vote in 2024?
In 2024, State Senate District 18, Idaho voted Republican by 10.3 points (R+10), carried by the Republican candidate. Out of 36,086 votes cast, 15,669 went Democratic and 19,399 went Republican.
What is State Senate District 18, Idaho's political archetype?
Akashic classifies State Senate District 18, 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 18, Idaho last vote Democratic?
The most recent presidential election in which State Senate District 18, Idaho voted Democratic was 1936.
How many people live in State Senate District 18, Idaho?
State Senate District 18, Idaho has a population of 70,027 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 18, Idaho?
Median household income in State Senate District 18, 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 18, Idaho?
Akashic tracks 38 presidential elections in State Senate District 18, 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.