Blog · September 24, 2026 · Idaho
Ada County, Idaho GIS Parcel Map Guide
Ada County’s free parcel map covers Boise and the Treasure Valley. Use it to trace property lines, check acreage and irrigation ditches, and look up owners by address or parcel number, even on last year’s farm field.
Main page: Ada County, ID GIS & Parcel Viewer (official map link, Ada County facts and neighboring maps).
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Boise and its neighbors have grown fast enough that last year’s hayfield can be this year’s subdivision. If you want to know what is really going on with a piece of ground in the Treasure Valley, start with Ada County’s official parcel map, the county-maintained ArcGIS viewer that links parcels to assessor data.
About Ada County’s parcel map
The viewer is published by Ada County on its own GIS server. It shows parcel boundaries, addresses, and aerial imagery, and each parcel opens a record with the parcel number, owner, acreage, and assessor information. Like most ArcGIS web apps, it has a search bar, identify tool, layer list, and basemap gallery.
Platbookmapper links to it from the Ada County row of our Idaho directory and from the national map.
Search by address or parcel number
- Open the Ada County GIS map.
- Search by address or parcel number. If you are unsure of the address format, zoom to the neighborhood and click instead.
- Read the parcel details: owner of record, acreage, and property type.
- Toggle aerial imagery and compare with the parcel lines to spot sheds, fences, or canals near the edges.
- Open the layer list for jurisdiction, zoning, or floodplain information if available.
- Save the parcel number with a dated screenshot.
How to find property lines in Ada County
- Click the parcel in the Ada County GIS map and note the parcel number and subdivision name.
- Get the recorded plat from the Ada County Recorder. Subdivision plats show lot dimensions and easements, including irrigation easements.
- On the ground, look for the corner pins. A ditch or old fence along the back is a clue, not a boundary.
- If the pins are missing, or you plan to fence, hire a surveyor.
Boise, Meridian, Eagle, Kuna, Star, and Garden City
Boise is the county seat and state capital, spreading from the Boise River up into the Foothills. Meridian, to the west, has grown into Idaho’s second-largest city. Eagle is known for larger lots and river-adjacent neighborhoods; Star and Kuna are the newer frontiers of subdivision growth; Garden City is a small city wrapped by Boise along the river. Micron Technology’s headquarters in Boise and the broader tech and healthcare economy have kept demand steady.
Every city has its own zoning and area of impact, a concept Idaho uses for planning just beyond city limits. Before you assume what a parcel can become, check which jurisdiction applies. Our zoning overlays guide explains how to read those boundaries.
Irrigation districts and former farmland
Much of western Ada County was irrigated farmland, and irrigation canals, laterals, and district easements still cross many properties. Districts such as the Nampa & Meridian Irrigation District deliver water to parts of the valley, and irrigation assessments can show up on a property even inside a subdivision. The parcel map will often show canals on the aerial; the irrigation district can tell you about delivery rights and easements. It is worth asking before you buy a parcel with a ditch along the back line.
The Foothills and the river corridor
North Boise’s Foothills offer views and trails, but slopes, wildfire exposure, and access roads all deserve attention. Along the Boise River, parcels may touch floodplain or greenbelt land, and river-adjacent lots can carry special development rules. Use the map’s aerial and any floodplain layers as a first screen, then talk to the city or county permitting staff. Our flood zones guide helps you read those layers.
Ada County acreage map and landowner lookups
If you want land rather than a lot, look to the southern and western edges of the county around Kuna and Star, and the desert rangeland farther south. Zoom out, turn on imagery, and look for large parcels without structures; then click each to see the owner and zoning context. Large public-land holdings — including federal land — show up as big blocks you cannot buy, so watch for those. For a systematic approach, see vacant land searches with county GIS.
Is there an Ada County plat book?
Not a commercial owner-name atlas. The free parcel map does that job, and recorded subdivision plats are filed with the Ada County Recorder. If you need older ownership, the Idaho State Archives and the Boise Public Library’s local history resources are good places to ask about historic maps of the valley. For hunting access, Idaho Fish and Game’s Access Yes! program opens some private land to the public by agreement. Otherwise, the parcel map’s owner field tells you whom to ask. An Idaho atlas and gazetteer is handy when your search wanders into the desert south of Kuna.
Is the Ada County GIS map accurate?
It’s accurate for identifying a parcel. It isn’t accurate enough to locate a fence. The Ada County Assessor maintains parcel and valuation data, and the lines are compiled from recorded plats and deeds. New subdivisions usually match well. Former farm parcels with ditches along the edges, and older rural tracts, can be off by a few feet or more. The Ada County Recorder holds deeds, plats and easements. Hire an Idaho licensed land surveyor for boundary questions. For eastern Idaho, see our Bonneville County parcel viewer guide, or browse the Idaho county GIS hub.
Treasure Valley mistakes, and what to do when the map won’t load
- Assuming a Boise mailing address means Boise zoning. Some Boise addresses are in unincorporated Ada County or another city’s area of impact.
- Ignoring the ditch. An irrigation lateral along a property line often carries an easement that limits fences and structures.
- Crossing the county line by accident. Canyon County begins just west of Star and Kuna; Nampa and Caldwell listings belong to a different assessor.
- Trusting on-screen measurements for a closing. Use the recorded plat or a survey.
If the map won’t load, reload it, turn off strict tracking protection for the county site, and use a desktop browser for layers. If a bookmark breaks, the Ada County row of our Idaho directory carries the current link.
Who uses it
Relocating buyers comparing Meridian and Eagle, builders tracking new plats, farmers and hobby-farm buyers, investors, surveyors, and title officers. Neighbors use it to see who owns the field next door when a development sign goes up.
Frequently asked questions
Who publishes the Ada County parcel map?
Ada County publishes it on its own GIS server, and the parcel data ties to Ada County Assessor records.
What is an area of impact in Idaho?
An area of impact is land just outside city limits where the city and county coordinate planning. It can affect what a parcel may become.
Why is my property line different on the GIS map?
County GIS lines are compiled for assessment and can be shifted from the surveyed corners, especially near ditches and on older farm parcels. The recorded plat and a survey control.
Where are Ada County deeds recorded?
With the Ada County Recorder, which holds deeds, plats and easements.
Open the official Ada County GIS viewer Ada County in the Platbookmapper directory
Not a survey. County GIS and tax parcel maps are assessment and planning layers. They are not a substitute for a recorded plat, deed, or licensed survey — especially for fences, setbacks, or boundary disputes.