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County · code 06035

Lassen CountyCalifornia

Lassen County is a California county with its seat in Susanville, formed in 1864 from parts of Plumas and Shasta counties. The county is named after Peter Lassen.

  • Founded1864
  • County seatSusanville
  • Named forPeter Lassen
  • Land area4,541 sq mi + 179 sq mi water
  • Population32,730 2020 Census
  • Parcels mapped33,333 checked 16 October 2026
Open the free map Click any parcel in Lassen County: acreage, parcel id, address and who publishes the map. No sign-in.

Updated

PlumasModocWashoe, NVSierraShasta Susanville Census outline · seat marked

Where it is

Lassen on the map of California

California has 58 counties and county equivalents, each with its own records office. Shapes with a page are links.

Alameda CountyAlpine CountyAmador CountyButte CountyCalaveras CountyColusa CountyContra Costa CountyDel Norte CountyEl Dorado CountyFresno CountyGlenn CountyHumboldt CountyImperial CountyInyo CountyKern CountyKings CountyLake CountyLos Angeles CountyMadera CountyMarin CountyMariposa CountyMendocino CountyMerced CountyModoc CountyMono CountyMonterey CountyNapa CountyNevada CountyOrange CountyPlacer CountyPlumas CountyRiverside CountySacramento CountySan Benito CountySan Bernardino CountySan Diego CountySan Francisco CountySan Joaquin CountySan Luis Obispo CountySan Mateo CountySanta Barbara CountySanta Clara CountySanta Cruz CountyShasta CountySierra CountySiskiyou CountySolano CountySonoma CountyStanislaus CountySutter CountyTehama CountyTrinity CountyTulare CountyTuolumne CountyVentura CountyYolo CountyYuba CountyLassen County Lassen
Counties of California · Lassen highlighted

History

Formed in 1864 from Plumas County and Shasta County

An old deed may name a county that no longer exists, or a boundary that has since moved.

Lassen County was created from Plumas and Shasta on April 1, 1864. It gained territory from Plumas in 1873 and 1901, and gained additional territory from Shasta in 1899. A small area was lost to Sierra County in 1874 when the boundary was set on public land survey lines.

Boundary changes from the Newberry Library, Atlas of Historical County Boundaries.

  1. 1864
    Lassen County created Lassen created from Plumas and Shasta.
    from Plumasfrom Shasta
    · Calif. Stats. 1863-1864, 15th sess., ch. 261/pp. 264-269
  2. 1866
    Boundary clarified Lassen boundaries clarified (no change).
    no change
    · Calif. Stats. 1865, 16th sess., ch. 371/p. 453
  3. 1873
    Gained territory Lassen gained from Plumas.
    from Plumas
    · Political Code 1872, 1: secs. 3912, 3920/pp. 115-116, 122-123
  4. 1874
    Lost territory Lassen lost small area to Sierra when boundary was set on public land survey lines.
    to Sierra
    · Calif. Stats. 1873, 20th sess., Acts Amendatory of the Codes, p. 166
  5. 1899
    Gained territory Lassen gained from Shasta.
    from Shasta
    · Calif. Stats. 1899, 33d sess., ch. 82/p. 98
  6. 1901
    Exchanged territory Lassen exchanged with Plumas.
    with Plumas
    · Calif. Stats. 1901, 34th sess., ch. 61/pp. 76-80

Land and parcels

What the maps cover in Lassen

Who publishes each layer, how good it is, and when we last checked.

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

Lassen by the Census

Population
32,730 2020 Census count
Housing units
12,216 2020 Census count
Land area
4,541 square miles
Water area
179 square miles
People per sq mi
7 population ÷ land area

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.

Inside a city or town, permits usually come from that city rather than the county.

Permits

County government

See your own lot on these maps

Open Lassen 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.

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Questions

Common questions about Lassen County

When was Lassen County founded?
Lassen County was founded in 1864, formed from Plumas County and Shasta County, and named after Peter Lassen.
What is the county seat of Lassen County?
The county seat of Lassen County is Susanville.
Is there an online parcel map for Lassen County?
Yes. A public source publishes a parcel map of 33,333 parcels, rated official here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.
Has Lassen County's boundary or name changed?
Lassen County was created in 1864 from Plumas County and Shasta County. Since then the Atlas of Historical County Boundaries records 4 later changes, chiefly involving Plumas County, Shasta County and Sierra County.
Who issues building permits in Lassen County?
The county's page on building permits: Building Permit Online Portal. Inside a city or town, ask that city first.
Is my lot in a flood zone?
We do not have flood maps for Lassen County yet. Look up the address on FEMA's Flood Map Service Center, which shows the effective flood map for any lot.

Nearby

Counties next door