When was Los Angeles County founded?

Los Angeles County was founded in 1850, and named after Los Angeles, California.

What is the county seat of Los Angeles County?

The county seat of Los Angeles County is Los Angeles.

Is there an online parcel map for Los Angeles County?

Yes. Los Angeles County publishes a parcel map of 2,433,213 parcels, rated good enough here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.

Has Los Angeles County's boundary or name changed?

Los Angeles County was created in 1850. Since then the Atlas of Historical County Boundaries records 12 later changes, chiefly involving San Bernardino County, Orange County and San Diego County.

Who issues building permits in Los Angeles County?

The county's page on building permits: Building Permits. Inside a city or town, ask that city first.

Who issues septic and well permits in Los Angeles County?

The county's page on septic systems and wells: Health department: septic and well.

Is my lot in a flood zone?

We do not have flood maps for Los Angeles County yet. Look up the address on FEMA's Flood Map Service Center, which shows the effective flood map for any lot.

County · code 06037

Los Angeles CountyCalifornia

Los Angeles County is a county in California, founded in 1850, with its seat at Los Angeles.

Founded1850
County seatLos Angeles
Named forLos Angeles, California
Land area4,059 sq mi + 690 sq mi water
Population10,014,009 2020 Census
Parcels mapped2,433,213 checked 15 October 2026

Open the free map Click any parcel in Los Angeles County: acreage, parcel id, address and who publishes the map. No sign-in.

Updated 19 October 2026

Census outline · seat marked

History

Founded in 1850

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

Los Angeles County was formed in 1850, and named after Los Angeles, California. Los Angeles is the county seat.

Boundary changes from the Newberry Library, Atlas of Historical County Boundaries; the 5 that matter most are shown first.

1850
Los Angeles County created Los Angeles created from non-county area. 18 February 1850 · Calif. Stats. 1849, 1st sess., ch. 15, sec. 3/p. 59
1851
Gained territory Los Angeles gained from Mariposa, exchanged with San Diego and Santa Barbara.
from Mariposa from San Diego from Santa Barbara
25 April 1851 · Calif. Stats. 1851, 2d sess., ch. 14, sec. 3/p. 172
1853
Lost territory Los Angeles lost to creation of San Bernardino.
to San Bernardino
26 April 1853 · Calif. Stats. 1853, 4th sess., ch. 78/pp. 119-123
1866
Lost territory Los Angeles lost to creation of Kern.
to Kern
2 April 1866 · Calif. Stats. 1865, 16th sess., ch. 569/pp. 796-798
1873
Lost territory Los Angeles lost to San Diego.
to San Diego
1 January 1873 · Political Code 1872, 1: secs. 3944-3945/pp. 140-142

Show all 15 changes (10 more, mostly small adjustments)

1850
Los Angeles County created Los Angeles created from non-county area. 18 February 1850 · Calif. Stats. 1849, 1st sess., ch. 15, sec. 3/p. 59
1851
Gained territory Los Angeles gained from Mariposa, exchanged with San Diego and Santa Barbara.
from Mariposa from San Diego from Santa Barbara
25 April 1851 · Calif. Stats. 1851, 2d sess., ch. 14, sec. 3/p. 172
1853
Lost territory Los Angeles lost to creation of San Bernardino.
to San Bernardino
26 April 1853 · Calif. Stats. 1853, 4th sess., ch. 78/pp. 119-123
1856
Boundary clarified Los Angeles boundaries redefined (no change).
no change
26 March 1856 · Calif. Stats. 1856, 7th sess., ch. 46/p. 53
1866
Lost territory Los Angeles lost to creation of Kern.
to Kern
2 April 1866 · Calif. Stats. 1865, 16th sess., ch. 569/pp. 796-798
1873
Lost territory Los Angeles lost to San Diego.
to San Diego
1 January 1873 · Political Code 1872, 1: secs. 3944-3945/pp. 140-142
1877
Lost territory Los Angeles lost to San Bernardino as a result of an official survey of the boundary.
to San Bernardino
5 February 1877 · Coy, 149, 217-219
c. 1881
Lost territory Los Angeles lost to Ventura as a result of an official boundary survey.
to Ventura
31 July 1881 · Coy, 150-154, 292
1889
Lost territory Los Angeles lost to creation of Orange. Act passed 11 March 1889; referendum for or against creation of new county held 4 June 1889.
to Orange
4 June 1889 · Calif. Stats. 1889, 28th sess., ch. 110/pp. 123-129
1919
Changed The new Political Code authorized Los Angeles to exchange with Ventura. This chapter of the 1919 revision of the laws did not take effect and was found unconstitutional by the California Supreme Court, 19 February 1920.
Ventura
23 July 1919 · Calif. Stats. 1919, 43d sess., ch. 470, secs. 3927, 3964/pp. 877-879, 908-909; "Mundell v. Lyons," in Calif. Rpts., 182:289-293
1987
Lost territory Los Angeles lost small area in Cypress Memorial Park Cemetery to Orange. Ordinance passed 29 July 1987; effective 1 September 1987.
to Orange
1 September 1987 · Minutes of the Board of Supervisors, Orange County, 29 July 1987, ordinance 3647
1992
Lost territory Los Angeles lost small area to San Bernardino. Ordinance passed 27 January 1992; effective 1 March 1992.
to San Bernardino
1 March 1992 · Minutes of the Board of Supervisors, San Bernardino County, 27 January 1992, ordinance 3478
1993
Lost territory Los Angeles lost small area to San Bernardino.
to San Bernardino
11 October 1993 · Calif. Stats. 1993-1994, reg. sess., ch. 1195, sec. 3/p. 6854
1999
Lost territory Los Angeles lost small area to Orange.
to Orange
30 September 1999 · Minutes of the Board of Supervisors, Los Angeles County, 24 August 1999, ordinance 99-0077M
2000
Boundary clarified Boundary between Los Angeles and Orange redefined to incorporate 1999 boundary change (no change).
with Orangeno change
19 September 2000 · Calif. Stats. 2000, reg. sess., ch. 506, secs. 15-16 in Official California Legislative Information, http://www.leginfo.ca.gov/statute.html, 23 September 2002

Land and parcels

What the maps cover in Los Angeles

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

Parcels Good enough

Lot lines and tax-map numbers for 2,433,213 parcels from Los Angeles County. Drawn for tax purposes: usually within a few feet of a survey, but not a survey.
checked 15 October 2026
Address points Missing

No public address points layer found for Los Angeles County yet.
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

Los Angeles by the Census

Population

10,014,009 2020 Census count

Housing units

3,591,981 2020 Census count

Land area

4,059 square miles

Water area

690 square miles

People per sq mi

2,467 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.

Records

Assessor and property recordsfrom lacounty.gov · checked 13 October 2026

Permits

Health department: septic and wellfrom lacounty.gov · checked 13 October 2026
Building Permitsfrom dpw.lacounty.gov
Health Permitsfrom lacounty.gov

Zoning and code

Planning and zoningfrom lacounty.gov · checked 13 October 2026
Zoningfrom planning.lacounty.gov

County government

County government
The official website of Los Angeles County.
lacounty.gov

See your own lot on these maps

Open Los Angeles 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.

Open the free map no sign-in Pro early access

Questions

Common questions about Los Angeles County

When was Los Angeles County founded?: Los Angeles County was founded in 1850, and named after Los Angeles, California.
What is the county seat of Los Angeles County?: The county seat of Los Angeles County is Los Angeles.
Is there an online parcel map for Los Angeles County?: Yes. Los Angeles County publishes a parcel map of 2,433,213 parcels, rated good enough here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.
Has Los Angeles County's boundary or name changed?: Los Angeles County was created in 1850. Since then the Atlas of Historical County Boundaries records 12 later changes, chiefly involving San Bernardino County, Orange County and San Diego County.
Who issues building permits in Los Angeles County?: The county's page on building permits: Building Permits. Inside a city or town, ask that city first.
Who issues septic and well permits in Los Angeles County?: The county's page on septic systems and wells: Health department: septic and well.
Is my lot in a flood zone?: We do not have flood maps for Los Angeles County yet. Look up the address on FEMA's Flood Map Service Center, which shows the effective flood map for any lot.

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