When was Jefferson County founded?

Jefferson County was founded in 1861, and named after Thomas Jefferson.

What is the county seat of Jefferson County?

The county seat of Jefferson County is Golden.

Is there an online parcel map for Jefferson County?

Yes. A public source publishes a parcel map of 253,767 parcels, rated fallback here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.

Has Jefferson County's boundary or name changed?

Jefferson County was created in 1861. Since then the Atlas of Historical County Boundaries records 32 later changes, chiefly involving Denver County, Broomfield County and Park County.

Who issues building permits in Jefferson County?

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

Who issues septic and well permits in Jefferson County?

The county's page on septic systems and wells: Contact Us page.

Is my lot in a flood zone?

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

County · code 08059

Jefferson CountyColorado

Jefferson County is a county in Colorado with its seat in Golden. It was created in 1861 and named after Thomas Jefferson.

Founded1861
County seatGolden
Named forThomas Jefferson
Land area764 sq mi + 9.7 sq mi water
Population582,910 2020 Census
Parcels mapped253,767 checked 15 October 2026

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

Updated 19 October 2026

Census outline · seat marked

History

Founded in 1861

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

Jefferson County was created on November 1, 1861, by Colorado Territory from non-county area. Starting in 1907, the county lost land to Park County, and from 1948 onward, it lost multiple areas to Denver through annexation, including Inspiration Point, Bear Valley, Green Meadows, and other neighborhoods.

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

1861
Jefferson County created Jefferson created by Colorado Territory from non-county area. 1 November 1861 · Colo. Terr. Laws 1861, 1st sess., sec. 24/p. 56
1907
Lost territory Jefferson lost to Park.
to Park
9 April 1907 · Colo. Laws 1907, 16th sess., ch. 142, p. 316
1948
Lost territory Jefferson lost to Denver; Inspiration Point, 48th Ave. & Sheridan Blvd.
to Denver
18 March 1948 · Annexation Map
1960
Lost territory Jefferson lost to Denver; Bear Valley, Yale Ave. & Sheridan Blvd.
to Denver
9 November 1960 · Annexation Map
1961
Lost territory Jefferson lost to Denver; Green Meadows, Evans Ave. & Sheridan Blvd.
to Denver
8 May 1961 · Annexation Map

Show all 35 changes (30 more)

1861
Jefferson County created Jefferson created by Colorado Territory from non-county area. 1 November 1861 · Colo. Terr. Laws 1861, 1st sess., sec. 24/p. 56
1889
Boundary clarified Jefferson boundaries were clarified (no change).
no change
20 April 1889 · Colo. Laws 1889, 7th sess., H.B. 256, pp. 100-101
1907
Lost territory Jefferson lost to Park.
to Park
9 April 1907 · Colo. Laws 1907, 16th sess., ch. 142, p. 316
1913
Boundary clarified Boundary between Jefferson and Gilpin was clarified (no change).
with Gilpinno change
8 May 1913 · Colo. Laws 1913, 19th sess., ch. 86/p. 284
1948
Lost territory Jefferson lost to Denver; Inspiration Point, 48th Ave. & Sheridan Blvd.
to Denver
18 March 1948 · Annexation Map
1960
Lost territory Jefferson lost to Denver; Bear Valley, Yale Ave. & Sheridan Blvd.
to Denver
9 November 1960 · Annexation Map
1961
Lost territory Jefferson lost to Denver; Green Meadows, Evans Ave. & Sheridan Blvd.
to Denver
8 May 1961 · Annexation Map
1962
Lost territory Jefferson lost to Denver; West Jewell, Depew St. & Jewell Ave.
to Denver
27 March 1962 · Annexation Map
1962
Lost territory Jefferson lost to Denver; West Bear Valley, Lamar St. & Yale Ave.
to Denver
31 July 1962 · Annexation Map
1962
Lost territory Jefferson lost to Denver; Inspiration Point Estates, Sheridan Blvd. & W. 52nd Ave.
to Denver
2 October 1962 · Annexation Map
1963
Lost territory Jefferson lost to Denver; Bear Valley Church, Yale Ave. & S. Lamar St.
to Denver
24 June 1963 · Annexation Map
1963
Lost territory Jefferson lost to Denver; Bear Valley South, Kenyon Ave. & S. Sheridan Blvd.
to Denver
9 July 1963 · Annexation Map
1964
Lost territory Jefferson lost to Denver; Bear Valley South #2, Kenyon Ave. & Harlan St., Bear Valley South #3, Kenyon Ave. & Sheridan Blvd.
to Denver
24 June 1964 · Annexation Map
1964
Lost territory Jefferson lost to Denver; Runyan, Sheridan Blvd. & W. 10th Ave.; Crosby, Hampden Ave. & Lamar St.
to Denver
20 October 1964 · Annexation Map
1966
Lost territory Jefferson lost to Denver; Fehlmann, W. Yale Ave. & S. Wadsworth Blvd.
to Denver
28 March 1966 · Annexation Map
1966
Gained territory Jefferson gained from Denver; Bear Valley South #1, #2, #3; W. Kenyon Ave. & S. Sheridan Blvd., when the area was de-annexed by court order.
from Denver
1 July 1966 · Annexation Map
1966
Lost territory Jefferson lost to Denver; Bear Valley Heights, W. Lehigh Ave. & S. Sheridan Blvd.
to Denver
22 August 1966 · Annexation Map
1967
Lost territory Jefferson lost to Denver; Bear Valley Heights #2, W. Kenyon Ave. Ext. & S. Sheridan Blvd.
to Denver
16 January 1967 · Annexation Map
1968
Lost territory Jefferson lost to Denver; Bear Valley Park, W. Teller Ave. & Bear Creek.
to Denver
22 January 1968 · Annexation Map
1969
Lost territory Jefferson lost to Denver; W. Inspiration Point, W. 52nd Ave. & Jay St. Ext.
to Denver
24 March 1969 · Annexation Map
1969
Lost territory Jefferson lost to Denver; Sheridan-Kenyon; S. Sheridan Blvd. & W. Hampden Ave.
to Denver
9 September 1969 · Annexation Map
1969
Lost territory Jefferson lost small area to Denver; Fehlman #2, W. Vassar Ave. & East of S. Wadsworth.
to Denver
21 November 1969 · Annexation Map
1969
Lost territory Jefferson lost to Denver; Pinehurst, W. Quincy Ave. & S. Sheridan Blvd.
to Denver
15 December 1969 · Annexation Map
1970
Lost territory Jefferson lost to Denver; Marston Lake #1, W. Quincy Ave. & Harlan St.
to Denver
9 February 1970 · Annexation Map
1970
Lost territory Jefferson lost to Denver; Marston Lake #2, W. Quincy Ave. & Wadsworth Blvd.-Sheridan Blvd.
to Denver
26 March 1970 · Annexation Map
1970
Lost territory Jefferson lost small area to Denver; Bear Valley Enclave, S. Lamar St. & W. Yale Ave.
to Denver
13 July 1970 · Annexation Map
1970
Lost territory Jefferson lost small area to Denver; Bear Valley Heights Enclave, S. Harlan & W. Kenyon.
to Denver
9 September 1970 · Annexation Map
1971
Lost territory Jefferson lost to Denver; Cavalier Annexation, W. Hampden Ave. & S. Harlan.
to Denver
9 October 1971 · Annexation Map
1971
Gained territory Jefferson gained from Denver when Cavalier Annex area (annexed to Denver on 9 October 1971) was de-annexed from Denver, but the entire area (with a small exception) was immediately re-annexed to Denver (no change).
from Denver
31 December 1971 · Annexation Map
1972
Lost territory Jefferson lost to Denver; West Marston, W. Quincy Ave. & S. Wadsworth.
to Denver
3 August 1972 · Annexation Map
1972
Lost territory Jefferson lost to Denver; Vaughn, W. Hampden Ave. & S. Harlan St.
to Denver
8 November 1972 · Annexation Map
1973
Lost territory Jefferson lost to Denver; Park West, W. Stanford Ave. & S. Kipling St.
to Denver
10 January 1973 · Annexation Map
c. 1980
Lost territory Jefferson lost to Denver.
to Denver
31 December 1980 · USGS, 7.5 Minute Series, various Colorado Quadrangles, 1971-2000
c. 1994
Lost territory Jefferson lost to Denver; W. Grant Ranch Blvd. & S. Estes St.
to Denver
31 December 1994 · USGS, 7.5 Minute Series, various Colorado Quadrangles, 1980-1994
2001
Lost territory Jefferson lost to creation of Broomfield.
to Broomfield
15 November 2001 · Colo. Laws 2001, 63d sess., ch. 103, pp. 256-274

Land and parcels

What the maps cover in Jefferson

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

Parcels Fallback

Lot lines and tax-map numbers for 253,767 parcels. Drawn for tax purposes: usually within a few feet of a survey, but not a survey. This copy is a fallback, not the county's own: use it as a guide and check the official record.
edited 18 April 2022 · checked 15 October 2026
Address points Missing

No public address points layer found for Jefferson 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

Jefferson by the Census

Population

582,910 2020 Census count

Housing units

248,429 2020 Census count

Land area

764 square miles

Water area

9.7 square miles

People per sq mi

763 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

Clerk of court: deeds and plats
Clerk & Recorder
from jeffco.us · checked 14 October 2026

Permits

Health department: septic and well
Public Health
from jeffco.us · checked 14 October 2026
Permitsfrom jeffco.us
Permit Feesfrom jeffco.us

Zoning and code

Land Development Regulationfrom jeffco.us
County Policies, Procedures and Ordinancesfrom jeffco.us
Planning & Zoningfrom jeffco.us
Planning & Zoningfrom jeffco.us

County government

County government
The official website of Jefferson County.
jeffco.us

See your own lot on these maps

Open Jefferson 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 Jefferson County

When was Jefferson County founded?: Jefferson County was founded in 1861, and named after Thomas Jefferson.
What is the county seat of Jefferson County?: The county seat of Jefferson County is Golden.
Is there an online parcel map for Jefferson County?: Yes. A public source publishes a parcel map of 253,767 parcels, rated fallback here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.
Has Jefferson County's boundary or name changed?: Jefferson County was created in 1861. Since then the Atlas of Historical County Boundaries records 32 later changes, chiefly involving Denver County, Broomfield County and Park County.
Who issues building permits in Jefferson County?: The county's page on building permits: Permits. Inside a city or town, ask that city first.
Who issues septic and well permits in Jefferson County?: The county's page on septic systems and wells: Contact Us page.
Is my lot in a flood zone?: We do not have flood maps for Jefferson County yet. Look up the address on FEMA's Flood Map Service Center, which shows the effective flood map for any lot.

Nearby