Union Mills, California
34 topographic sheets cover this place, the earliest surveyed in 1891 and the latest in 1992. It stands in the Donner census division. It lies in ZIP code area 96161. It lies near Union Valley. The Survey maps it on the Martis Peak quadrangle. It stands 5,853 feet above sea level.
Then and now
1891 to 1992The same ground, surveyed 101 years apart. Drag the handle to wipe between them. Both sheets are United States Geological Survey originals; neither has been altered.


Topographic sheets covering this place
11 surveys from 34 printed sheetsMatched by testing this settlement's coordinate against the published boundary of every sheet in the United States Geological Survey's historical collection. Each opens the scanned sheet at the Survey.
- 1891 USGS Truckee quadrangle1:125000
- 1893 USGS Truckee quadrangle1:125000
- 1895 USGS Truckee quadrangle1:125000, 9 printings
- 1932 USGS Truckee quadrangle1:96000
- 1940 USGS Truckee quadrangle1:125000, 4 printings
- 1955 USGS Martis Peak quadrangle1:24000, 5 printings
- 1955 USGS Truckee quadrangle1:62500, 4 printings
- 1958 USGS Chico quadrangle1:250000, 4 printings
- 1960 USGS Chico quadrangle1:250000
- 1977 USGS Truckee quadrangle1:100000, 2 printings
- 1992 USGS Martis Peak quadrangle1:24000, 2 printings
Fires near this place
256 since 1992Regional context, not property-specific evidence. The federal wildfire occurrence database lists 256 fires within 5 miles of Union Mills between 1992 and 2020, burning about 2,514 acres in total. 35 started naturally. 14 were recorded as arson. Distance is straight-line from the map coordinates, so a fire counted here may appear on a neighbouring settlement's page as well.
| Reported cause | Fires |
|---|---|
| Missing data/not specified/undetermined | 77 |
| Recreation and ceremony | 67 |
| Natural | 35 |
| Equipment and vehicle use | 28 |
| Arson/incendiarism | 14 |
| Debris and open burning | 13 |
| Misuse of fire by a minor | 9 |
| Smoking | 8 |
| Power generation/transmission/distribution | 4 |
| Fireworks | 1 |
The most recent of them, most recent first, with the day each was reported and the service that recorded it.
| Date | Cause | Size | Reported by | Name on the report |
|---|---|---|---|---|
| 9 September 2019 | Missing data/not specified/undetermined | 3.0 acres | Tahoe National Forest | RESERVOIR |
| 9 September 2013 | Recreation and ceremony | 1.0 acres | Nevada-Yuba-Placer Unit | AIRPORT |
| 8 September 2017 | Missing data/not specified/undetermined | under an acre | California Department of Forestry & Fire Protection | QUARRY |
| 5 September 1994 | Equipment and vehicle use | under an acre | Nevada-Yuba-Placer Unit | AIRPLANE |
| 4 September 2019 | Recreation and ceremony | under an acre | Tahoe National Forest | BOCA |
| 4 September 1998 | Natural | under an acre | Humboldt-Toiyabe National Forest | GREY |
| 4 September 1993 | Recreation and ceremony | under an acre | Nevada-Yuba-Placer Unit | SOMERSET |
| 30 September 2020 | Missing data/not specified/undetermined | 3.0 acres | Nevada-Yuba-Placer Unit | GOLD |
Settlements close enough to share some of these fires:
Mines and quarries near this place
6 within 5 milesRegional context, not property-specific evidence. The federal mineral resources record lists 6 workings within 5 miles of Union Mills: 5 producers, 1 past producer. 5 still produce. What was taken out: Sand and Gravel, Construction, Pumice. Distance is straight-line from the map coordinates, so a quarry counted here may appear on a neighbouring settlement's page as well.
| Where | Site | Commodity | Status | Recorded |
|---|---|---|---|---|
| Hirschdale Pit | Pumice | Producer | ||
| Red Rock Aggregates | Pumice | Producer | ||
| Martis Valley Pit | Sand and Gravel, Construction | Producer | ||
| Sha-Neva-Plant No. 2 | Sand and Gravel, Construction | Past Producer | ||
| Teichert Aggregates Truckee Pit | Sand and Gravel, Construction | Producer | ||
| Truckee Pit | Sand and Gravel, Construction | Producer |
Nearest settlements
The eight closest, with where each one stands in the county. Distances are straight-line, computed from the Geographic Names Information System coordinates.
| Map | Place | Distance | Sheets |
|---|---|---|---|
| Prosser (historical) | 1.5 miles | 36 | |
| Polaris | 1.8 miles | 36 | |
| Hirschdale | 1.9 miles | 34 | |
| Hinton | 2.3 miles | 35 | |
| Boca | 2.3 miles | 35 | |
| Olympic Heights | 3.0 miles | 36 | |
| Prosser Lakeview Estates | 3.4 miles | 36 | |
| Ponderosa Fairway Estates | 3.5 miles | 36 |
Elsewhere
Matched on this settlement's Geographic Names Information System number rather than its name, so it cannot be a different place of the same name in another state.
| Wikidata item Q7885838 | The structured record the population and elevation above come from. Public domain (CC0). |
Provenance
This settlement is recorded in the Geographic Names Information System as feature 1660080. The sheet list is computed by point-in-boundary test against the United States Geological Survey's historical topographic inventory. Both are works of the United States government and carry no copyright under 17 U.S.C. 105.
Wildfire. Short, Karen C. 2022. Spatial wildfire occurrence data for the United States, 1992-2020 [FPA_FOD_20221014]. 6th Edition. Fort Collins, CO: Forest Service Research Data Archive. https://doi.org/10.2737/RDS-2013-0009.6 Collected with United States Government funding and usable without additional permissions or fees.
Mines and quarries. USGS Mineral Resources Data System (MRDS) https://mrdata.usgs.gov/mrds/ A work of the United States government, no copyright under 17 U.S.C. 105.










