The short version.
Idaho nominates most candidates through a partisan primary: each party holds its own primary in May of even-numbered years, and the winners advance to the November general election. To get on the ballot you file a declaration of candidacy and pay a filing fee, or, in place of the fee, submit a petition in lieu of the filing fee (Idaho Code § 34-626). County and local candidates file with the Ada County Clerk; state, legislative, judicial, and federal candidates file with the Idaho Secretary of State.
This page covers how that works for Ada County. It is not legal advice. Your county clerk and the Idaho Secretary of State's candidate-filing page are the sources of truth.
Ada County at the ballot box.
- In 2024, Ada County cast 267,340 votes for president: 53.8% Republican, 43.4% Democratic.
- Turnout has moved from 259,389 votes in 2020 to 267,340 in 2024.
Public presidential-election returns for Ada County. A registration edge in a primary is often decided by a few hundred reliable voters, which is where a real field operation pays off.
How to get on the ballot in Idaho.
The campaigns that win the field are the ones who start building their list of supporters and volunteers before qualifying even opens, not after. The Ada County voter file is already loaded in Motion51, so you can start finding your people now.
There are two routes onto the ballot, and both start with a declaration of candidacy filed during the official window.
Path 1: Run in a party primary.
File a declaration of candidacy during the filing period and include either the filing fee or a petition in lieu of the fee. The fee amount and the number of petition signatures depend on the office. A note on Idaho's primary: the Republican primary is closed (only voters affiliated with the party may vote in it), while other parties may open their primary to unaffiliated voters. Winning your party's primary puts you on the November ballot.
Path 2: Run as an independent or for a nonpartisan office.
Independent candidates file a declaration with a petition of qualified electors and go straight to the November general ballot. Nonpartisan races (judicial seats and many city, school, and special-district offices) run on their own calendars and filing rules.
How the filing calendar works.
Idaho's calendar repeats every cycle even though the exact dates shift year to year:
- The primary election is held in May of even-numbered years; the general election is the first Tuesday after the first Monday in November.
- The candidate filing window opens in late winter and closes in spring (the 2026 window has closed; the next is early 2028). The deadline for state, federal, legislative, and judicial candidates falls a couple of weeks before the deadline for county, local, district, and precinct-committeeman candidates.
- Write-in candidates file a separate declaration of intent closer to the election.
Key Idaho dates.
2028: sheriff and prosecuting attorney return
Idaho county offices are not one even-year block. Clerk, treasurer, assessor and coroner were on the 2026 ballot and next run in 2030. SHERIFF and PROSECUTING ATTORNEY are 2028 offices, along with two of the three commissioner seats.
- Tue May 18 and Tue Nov 2, 2027 COMPUTED. Idaho now has only two election dates a year (Idaho Code sec. 34-106(1)): the third Tuesday in May and the Tuesday after the first Monday in November. The March and August dates were repealed. City general elections are the November one.
- Mon Feb 28 to Fri Mar 10, 2028 COMPUTED declaration-of-candidacy window for county office, the twelfth Monday to the tenth Friday before the primary (sec. 34-704(3)).
- Fri Mar 17, 2028, 5:00 p.m. COMPUTED county WRITE-IN declaration deadline -- again before the primary (sec. 34-702A(3)).
- Tue May 16, 2028 COMPUTED primary, the third Tuesday in May (sec. 34-601).
- Tue Nov 7, 2028 COMPUTED general election.
Status as of November 4, 2026: dates that have passed are greyed out and marked CLOSED.
The 2026 dates come from the Idaho Secretary of State's 2026 election calendar and Idaho Code title 34, read on 2026-08-20. No 2027 or 2028 calendar exists yet -- county clerks must publish the 2027 one by December 31, 2026 -- so those dates are arithmetic from statute; the same arithmetic reproduces the published 2026 dates exactly. Confirm with your county clerk.
The 2027 ballot in Ada County.
These 2027 dates are confirmed against the state's own published calendar or statute. Anything our research could not confirm is left off this page rather than estimated.
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November 2, 2027
General — Mixed.
Which local offices are on this ballot varies by jurisdiction; the Ada County Clerk can tell you which of yours is.
Candidate filing: opens Aug 16, 2027, closes Aug 27, 2027.
Source 1 · Source 2
2027 dates can move, and a municipality can change its own election date by ordinance. Which seats are on a given ballot depends on when each was last filled. Confirm anything you are relying on with the Ada County Clerk before you act on it.
Ada County at a glance.
Ada County had an estimated 535,799 residents in July 2024, the most populous of Idaho's 44 counties, up 8.2% since the 2020 census. Of those, 422,901 are 18 or older, the voting-age population, and 17.3% are 65 or older. Its 301,507 active registered voters equal about 71.3% of that voting-age population.
It covers 1,052 square miles of land (509 people per square mile), and 12.0% of residents live outside any incorporated city or town. The largest cities and towns are Boise City (237,963), Meridian (139,740), Eagle (33,451), Kuna (29,127) and Star (part) (18,155). The American Community Survey (2020-2024) puts it at a median age of 38.4, a median household income of $91,502, 44.6% of adults 25 and older holding a bachelor's degree or higher and 70.8% of occupied homes owned by the people living in them.
In 2024, 267,340 votes were cast for president, about 63.2% of the voting-age population; the Democratic ticket took 43.4% and the Republican ticket 53.8%. The two-party margin moved from R+6.2 in 2008 to R+10.4 in 2024.
- Population (2024 estimate)
- 535,799
- Population (2020 census base)
- 494,969
- Voting-age population (18+)
- 422,901
- Active voters per 100 adults
- 71.3
- Residents 65 and older
- 17.3%
- People per square mile
- 509
- Living outside incorporated places
- 12.0%
- Land area
- 1,052 sq mi
- Median age
- 38.4
- Median household income
- $91,502
- Adults 25+ with a bachelor's degree
- 44.6%
- Owner-occupied homes
- 70.8%
Largest cities and towns
- Boise City 237,963
- Meridian 139,740
- Eagle 33,451
- Kuna 29,127
- Star (part) 18,155
Presidential vote, 2008–2024
| Year | Democratic | Republican | Margin | Votes cast |
|---|---|---|---|---|
| 2024 | 43.4% | 53.8% | R+10.4 | 267,340 |
| 2020 | 46.5% | 50.4% | R+3.9 | 259,389 |
| 2016 | 38.7% | 47.9% | R+9.2 | 195,587 |
| 2012 | 42.7% | 54.0% | R+11.3 | 180,361 |
| 2008 | 45.8% | 52.0% | R+6.2 | 179,402 |
Sources: U.S. Census Bureau Vintage 2024 population estimates and 2024 Gazetteer; American Community Survey 2020–2024 5-year estimates; certified county presidential returns. Growth, density and turnout are simple arithmetic on those figures.
Counties next to Ada.
Running in a district that crosses a county line? Each of these has its own guide.
Registered voters, the most reliable-voting precincts and how this county has voted: Ada County voter data.
Offices on the ballot.
Idaho voters elect federal offices (U.S. House and Senate); statewide constitutional offices (Governor, Lieutenant Governor, Secretary of State, and others); the Idaho Legislature (State Senate and House); judicial offices; county offices such as commissioner, sheriff, clerk, assessor, treasurer, coroner, and prosecuting attorney; precinct committeemen; and city, school, and special-district seats.
For the official list of Ada County seats up in a given cycle, check with your county clerk below.
Your county clerk.
Idaho runs elections through its 44 county clerks. The Ada County Clerk is where county and local candidates file, and the source of truth for local dates, districts, signature counts, and forms.
- Clerk
- Trent Tripple
- Office
- 400 N. Benjamin Lane, Ste 100, Boise, ID 83704
- Phone
- (208) 287-6860
- Website
- https://adacounty.id.gov/elections/
Contact details verified 2026-07-22. If a field is wrong or out of date, the official VoteIdaho.gov clerk directory is the canonical source.
After you qualify: building a field operation.
The paperwork ends the day you file. What starts then is the actual campaign: knocking on doors, recruiting volunteers, and identifying the voters who'll show up for you in the primary and in November.
That's what Motion51 is built for. The Ada County voter file is already loaded: no chasing a CSV or paying a vendor. You scope your district, recruit volunteers, cut turf, and start knocking. The app works offline for areas with bad cell coverage, and every door is logged with a timestamp.
If qualifying is settled and you're thinking about the field operation, our For Candidates page walks through the next steps.