County · code 33007
Coos CountyNew Hampshire
Coos County is a New Hampshire county with its seat in Lancaster, created in 1805.
- Founded1805
- County seatLancaster
- Land area1,795 sq mi + 36 sq mi water
- Population31,268 2020 Census
- Parcels mapped25,989 checked 14 October 2026
Where it is
Coos on the map of New Hampshire
New Hampshire has 10 counties and county equivalents, each with its own records office. Shapes with a page are links.
History
Formed in 1805 from Grafton County
An old deed may name a county that no longer exists, or a boundary that has since moved.
Coos County was created from Grafton County on March 1, 1805, and gained Nash and Sawyers Location gore from Grafton later that year. Over the next fifty years, the county lost land to neighboring counties: the town of Chatham to Strafford County in 1823, and the towns of Bartlett and Jackson and Hart's Location gore to Carroll County in 1853, with Hale's Location gore following to Carroll County the same year.
- 1805Coos County created Coos created from Grafton. · N.H. Early Laws, vol. 7, ch. 33 [1803]/pp. 206-207
- 1805Gained territory Coos gained Nash and the gore of Sawyers Location from Grafton. · N.H. Early Laws, vol. 7, ch. 15 [1805]/pp. 398-399
- 1823Lost territory Coos lost town of Chatham to Strafford. · N.H. Early Laws, vol. 9, ch. 30 [1823], sec. 1/p. 210
- 1829Boundary clarified Coos boundaries were redefined (no change).no change· N.H. Early Laws, vol. 9, ch. 100 [1829], sec. 1/pp. 879-882
- 1853Lost territory Coos lost to Grafton. Coos lost towns of Bartlett and Jackson and the gore of Hart's Location to Carroll; Hale's Location remained part of Coos, although it was surrounded by Carroll. · N.H. Laws 1853, ch. 1290, sec. 1/p. 1230
- 1853Lost territory Coos lost the gore of Hale's Location to Carroll. · N.H. Laws 1853, ch. 1425, sec. 1/p. 1348
- 1875Boundary clarified Boundary between Coos and Grafton was redefined (no change).with Graftonno change· N.H. Laws 1875, ch. 31, sec. 1/p. 457
Land and parcels
What the maps cover in Coos
Who publishes each layer, how good it is, and when we last checked.
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Parcels Good enough
Lot lines and tax-map numbers for 25,989 parcels from New Hampshire Geographic Information System Clearinghouse (GRANIT). Drawn for tax purposes: usually within a few feet of a survey, but not a survey.
checked 14 October 2026 -
Address points Missing
No public address points layer found for Coos County yet.
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Buildings Reference
Roof outlines traced from aerial imagery from FEMA Response Geospatial Office with Oak Ridge National Laboratory (ORNL). Good for seeing what is on a lot; not accurate enough to set a fence from.
checked 18 October 2026
- Official
- from the office that keeps the record
- Good enough
- a reliable statewide or national copy
- Fallback
- a guide only; check the official record
- Missing
- nothing public found yet
People and land
Coos by the Census
Source: US Census Bureau, 2020 Census; US Census Bureau, 2020 Gazetteer Files. Not endorsed or certified by the Census Bureau.
Rules and offices
Who to ask before you build, dig or sell
Official county pages only. We link to them; we do not copy them, because they change.
In New Hampshire, permits, zoning and assessing are handled by each city or town, not the county, and deeds are recorded at the county's registry of deeds.
Zoning and code
County government
- County government
The official website of Coos County.
See your own lot on these maps
Open Coos County on Parcel Chart's free map and click your parcel. Save it with a free account; the full record of your place (site map, projects, documents) is Pro, in early access.
Questions
Common questions about Coos County
- When was Coos County founded?
- Coos County was founded in 1805, formed from Grafton County.
- What is the county seat of Coos County?
- The county seat of Coos County is Lancaster.
- Is there an online parcel map for Coos County?
- Yes. New Hampshire Geographic Information System Clearinghouse (GRANIT) publishes a parcel map of 25,989 parcels, rated good enough here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.
- Has Coos County's boundary or name changed?
- Coos County was created in 1805 from Grafton County. Since then the Atlas of Historical County Boundaries records 4 later changes, chiefly involving Carroll County, Grafton County and Strafford County.
- Is my lot in a flood zone?
- We do not have flood maps for Coos County yet. Look up the address on FEMA's Flood Map Service Center, which shows the effective flood map for any lot.
Nearby