Unionville, California

The same ground, surveyed 109 years apart. Drag the handle to wipe between them. Both sheets are United States Geological Survey originals; neither has been altered.

1891 2000

Matched 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 Colfax quadrangle1:125000
• 1892 USGS Colfax quadrangle1:125000
• 1894 USGS Colfax quadrangle1:125000
• 1898 USGS Colfax quadrangle1:125000
• 1900 USGS Colfax quadrangle1:125000
• 1902 USGS Colfax quadrangle1:125000, 7 printings
• 1938 USGS Colfax quadrangle1:125000, 3 printings
• 1949 USGS Alleghany quadrangle1:24000, 5 printings
• 1950 USGS Alleghany quadrangle1:62500, 4 printings
• 1951 USGS Alleghany quadrangle1:24000
• 1958 USGS Chico quadrangle1:250000, 4 printings
• 1960 USGS Chico quadrangle1:250000
• 1977 USGS Truckee quadrangle1:100000, 2 printings
• 2000 USGS Alleghany quadrangle1:24000

Regional context, not property-specific evidence. The federal wildfire occurrence database lists 50 fires within 5 miles of Unionville (historical) between 1992 and 2020, burning about 126 acres in total. 20 started naturally. 1 was 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.

The most recent of them, most recent first, with the day each was reported and the service that recorded it.

Settlements close enough to share some of these fires:

• Alleghany
• Centerville (historical)
• Forest
• Minnesota Flat
• Plumbago
• American Hill (historical)

Every fire recorded in Sierra County

Regional context, not property-specific evidence. The federal mineral resources record lists 406 workings within 5 miles of Unionville (historical): 193 past producers, 123 occurrences, 43 producers, 37 unknowns. 44 still produce. What was taken out: Gold, Silver, Chromium, Platinum. Distance is straight-line from the map coordinates, so a quarry counted here may appear on a neighbouring settlement's page as well.

Every working recorded in Sierra County

The eight closest, with where each one stands in the county. Distances are straight-line, computed from the Geographic Names Information System coordinates.

This settlement is recorded in the Geographic Names Information System as feature 1733188. 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.