What is the county seat of Gallatin County?

The county seat of Gallatin County is Bozeman.

Is there an online parcel map for Gallatin County?

Yes. Gallatin County publishes a parcel map of 38,498 parcels, rated good enough here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.

Has Gallatin County's boundary or name changed?

Gallatin County was created in 1865 from Jefferson County, Madison County, Big Horn County and Custer County. Since then the Atlas of Historical County Boundaries records 18 later changes, chiefly involving Meagher County, Custer County and Madison County.

Is my lot in a flood zone?

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

County · code 30031

Gallatin CountyMontana

Gallatin County is a county in Montana, with its seat in Bozeman, formed on February 2, 1865.

Founded1865
County seatBozeman
Named forAlbert Gallatin
Land area2,605 sq mi + 28 sq mi water
Population118,960 2020 Census
Parcels mapped38,498 checked 15 October 2026

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

Updated 20 October 2026

Census outline · seat marked

History

Formed in 1865 from Jefferson County, Madison County, Big Horn County and Custer County

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

Gallatin County was created by Montana Territory from Jefferson and Madison counties, with Big Horn (now Custer) attached for legislative and judicial purposes. The county was named after Albert Gallatin. Gallatin underwent numerous boundary changes in its early years, exchanging territory with Madison and Jefferson counties and gaining lands from Meagher, Custer, and from territory transferred from Dakota Territory.

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

1865
Gallatin County created Gallatin created by Montana Territory from Jefferson and Madison. Big Horn (original, now Custer) not fully organized, attached to Gallatin "for legislative and judicial purposes."
from Jefferson from Madison from Big Horn from Custer
2 February 1865 · Mont. Terr. Laws 1864, 1st leg., secs. 7, 9/pp. 530-531
1866
Lost territory Gallatin lost to creation of Meagher. Acts of the 2d and 3d legislatures were declared null and void by the United States Congress, 2 March 1867.
to Meagher
26 March 1866 · Mont. Terr. Laws 1866, 2d leg., ch. 10/pp. 11-12; U.S. Stat., vol. 14, ch. 150 [1867], sec. 6/p. 427; Burlingame and Toole, 1:219-228; Sanders, Helen F., 1:331-341
1867
Gained territory Gallatin gained all of Meagher; Meagher eliminated when the United States Congress declared null and void all acts passed by the 2d and 3d legislative assemblies of Montana Territory.
from Meagher
2 March 1867 · U.S. Stat., vol. 14, ch. 150 [1867], sec. 6/p. 427; Burlingame and Toole, 1:219-228; Sanders, Helen F., 1:331-341
1867
Lost territory Gallatin lost to re-creation of Meagher.
to Meagher
16 November 1867 · Mont. Terr. Laws 1867, 4th leg., pp. 99-100
1889
Became part of Montana Gallatin became a county in the state of Montana. 8 November 1889 · U.S. Stat., vol. 26, pp. 1551-1552 and vol. 25, ch. 180 [1889]/pp. 676-684; Swindler, 6:82-83

Show all 20 changes (15 more)

1865
Gallatin County created Gallatin created by Montana Territory from Jefferson and Madison. Big Horn (original, now Custer) not fully organized, attached to Gallatin "for legislative and judicial purposes."
from Jefferson from Madison from Big Horn from Custer
2 February 1865 · Mont. Terr. Laws 1864, 1st leg., secs. 7, 9/pp. 530-531
1866
Lost territory Gallatin lost to creation of Meagher. Acts of the 2d and 3d legislatures were declared null and void by the United States Congress, 2 March 1867.
to Meagher
26 March 1866 · Mont. Terr. Laws 1866, 2d leg., ch. 10/pp. 11-12; U.S. Stat., vol. 14, ch. 150 [1867], sec. 6/p. 427; Burlingame and Toole, 1:219-228; Sanders, Helen F., 1:331-341
1867
Gained territory Gallatin gained all of Meagher; Meagher eliminated when the United States Congress declared null and void all acts passed by the 2d and 3d legislative assemblies of Montana Territory.
from Meagher
2 March 1867 · U.S. Stat., vol. 14, ch. 150 [1867], sec. 6/p. 427; Burlingame and Toole, 1:219-228; Sanders, Helen F., 1:331-341
1867
Lost territory Gallatin lost to re-creation of Meagher.
to Meagher
16 November 1867 · Mont. Terr. Laws 1867, 4th leg., pp. 99-100
1867
Gained territory Gallatin gained from Jefferson.
from Jefferson
2 December 1867 · Mont. Terr. Laws 1867, 4th leg., pp. 104-105
1867
Exchanged territory Gallatin exchanged with Madison.
with Madison
10 December 1867 · Mont. Terr. Laws 1867, 4th leg., sec. 3/p. 103
1872
Changed Attachment of Big Horn (original, now Custer) to Gallatin "for judicial purposes" was confirmed.
Big Horn Custer
4 January 1872 · Mont. Terr. Laws 1871, 7th leg., ch. 77/p. 585
1872
Lost territory Gallatin lost to Big Horn (original, now Custer); Big Horn remained attached to Gallatin "for legislative and judicial purposes."
to Big Horn to Custer
12 January 1872 · Mont. Terr. Laws 1871, 7th leg., ch. 20, secs. 8, 11/pp. 431-432
1874
Gained territory Gallatin gained small remnant of Dakota Territory which was transferred to Montana Territory on 17 February 1873. This act, which appears to have been based on faulty maps, assigned the area to Beaverhead and Madison, however, it was actually surrounded by Gallatin.
from Beaverhead from Madison
7 February 1874 · Mont. Terr. Laws 1874, 8th leg., p. 68; Van Zandt, 136, 145, 150; De Lacy, Map of the Territory of Montana
1874
Lost territory Gallatin lost to Meagher.
to Meagher
13 February 1874 · Mont. Terr. Laws 1874, 8th leg., pp. 66-67
1877
Changed Custer fully organized, detached from Gallatin.
Custer
14 June 1877 · History of Montana 1739-1885, p. 517
1882
Gained territory Gallatin gained from Custer. The area included all territory ceded by the Crow Indians to the United States on 12 June 1880; the United States Congress ratified the cession on 11 April 1882. Montana Territorial Legislature passed this act 14 February 1881 to take effect upon ratification of the treaty by the U. S. Congress.
from Custerfrom U. S.
11 April 1882 · Mont. Terr. Laws 1881, 12th leg., p. 124; Royce, 900-901, 904-905, pl. 39
1883
Lost territory Gallatin lost to creation of Yellowstone.
to Yellowstone
26 February 1883 · Mont. Terr. Laws 1883, 13th leg., pp. 119-122
1887
Boundary clarified Gallatin boundaries redefined (no change).
no change
1 March 1887 · Mont. Terr. Laws 1887, 15th leg., secs. 737, 742/pp. 836-837, 839-840
1887
Lost territory Gallatin lost to creation of Park; Park not fully organized, attached to Gallatin "for judicial purposes." Gallatin lost that part of Yellowstone National Park located in Montana, which was excluded from county jurisdiction and became a non-county area. Act passed 23 February 1887; took effect 1 May 1887.
to Park
1 May 1887 · Mont. Terr. Laws 1887, 15th leg., pp. 1238-1242
1887
Changed Park fully organized, detached from Gallatin.
Park
1 August 1887 · Mont. Terr. Laws 1887, 15th leg., sec. 11/p. 1242
1889
Became part of Montana Gallatin became a county in the state of Montana. 8 November 1889 · U.S. Stat., vol. 26, pp. 1551-1552 and vol. 25, ch. 180 [1889]/pp. 676-684; Swindler, 6:82-83
1913
Exchanged territory Gallatin boundaries adjusted to run on federal land survey lines: Gallatin exchanged with Madison and Park; gained small areas from Broadwater and Meagher.
with Madison with Park with Broadwater with Meagher
8 March 1913 · Mont. Laws 1913, 13th leg., ch. 60/pp. 113-116
1929
Lost territory Gallatin lost territory as the boundaries of Yellowstone National Park were expanded. County boundaries were defined to exclude land within Yellowstone National Park. 1 March 1929 · U.S. Stat., vol. 45, ch. 437 [1929]/pp. 1435-1436; Haines, 2: 325-331
1978
Gained territory Gallatin gained part of Yellowstone National Park, which had remained a non-county area in Montana. Act passed 19 April 1977; approved by Gallatin voters 7 November 1978. 7 November 1978 · Mont. Laws 1977, 45th leg., ch. 447/pp. 1407-1411; Montana Code Annotated, "Descriptions--County Boundaries," 33

Land and parcels

What the maps cover in Gallatin

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

Parcels Good enough

Lot lines and tax-map numbers for 38,498 parcels from Gallatin County. Drawn for tax purposes: usually within a few feet of a survey, but not a survey.
edited 6 December 2023 · checked 15 October 2026
Address points Official

One point per address, 74,440 in all from Montana State Library.
edited 13 October 2026 · checked 14 October 2026
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

Gallatin by the Census

Population

118,960 2020 Census count

Housing units

52,835 2020 Census count

Land area

2,605 square miles

Water area

28 square miles

People per sq mi

46 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

Gallatin County's official site

We have found the county's site but not its offices yet; start there.

County government

County government
The official website of Gallatin County.
gallatin.mt.gov

See your own lot on these maps

Open Gallatin 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 Gallatin County

When was Gallatin County founded?: Gallatin County was founded in 1865, formed from Jefferson County, Madison County, Big Horn County and Custer County, and named after Albert Gallatin.
What is the county seat of Gallatin County?: The county seat of Gallatin County is Bozeman.
Is there an online parcel map for Gallatin County?: Yes. Gallatin County publishes a parcel map of 38,498 parcels, rated good enough here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.
Has Gallatin County's boundary or name changed?: Gallatin County was created in 1865 from Jefferson County, Madison County, Big Horn County and Custer County. Since then the Atlas of Historical County Boundaries records 18 later changes, chiefly involving Meagher County, Custer County and Madison County.
Is my lot in a flood zone?: We do not have flood maps for Gallatin County yet. Look up the address on FEMA's Flood Map Service Center, which shows the effective flood map for any lot.

Nearby