Ohmer, California

The same ground, surveyed 87 years apart. Drag the handle to wipe between them. Both sheets are United States Geological Survey originals; neither has been altered.

1896 1983

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.

• 1896 USGS Carquinez Strait quadrangle1:62500
• 1898 USGS Karquines quadrangle1:62500
• 1901 USGS Carquinez quadrangle1:62500, 5 printings
• 1901 USGS Karquines quadrangle1:62500
• 1902 USGS Napa quadrangle1:125000, 6 printings
• 1940 USGS Carquinez Strait quadrangle1:62500, 2 printings
• 1942 USGS Carquinez quadrangle1:62500
• 1947 USGS Santa Rosa quadrangle1:250000
• 1949 USGS Santa Rosa quadrangle1:250000, 2 printings
• 1951 USGS Port Chicago quadrangle1:24000, 2 printings
• 1958 USGS Santa Rosa quadrangle1:250000, 3 printings
• 1959 USGS Port Chicago quadrangle1:24000, 2 printings
• 1959 USGS Vine Hill quadrangle1:24000, 3 printings
• 1962 USGS Santa Rosa quadrangle1:250000
• 1964 USGS Santa Rosa quadrangle1:250000
• 1968 USGS Port Chicago quadrangle1:24000
• 1983 USGS Napa quadrangle1:100000

Regional context, not property-specific evidence. The federal wildfire occurrence database lists 536 fires within 5 miles of Ohmer (historical) between 1992 and 2020, burning about 1,670 acres in total. 2 started naturally. 102 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.

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:

• Concord
• Clyde
• Nichols
• Port Chicago (historical)
• McAvoy
• Monsanto

Every fire recorded in Contra Costa County

Regional context, not property-specific evidence. The federal mineral resources record lists 26 workings within 5 miles of Ohmer (historical): 11 occurrences, 6 past producers, 4 prospects, 3 producers. 3 still produce. What was taken out: Stone, Stone, Crushed/Broken, Pumice, Calcium. 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 Contra Costa County

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

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.

This settlement is recorded in the Geographic Names Information System as feature 1732469. 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.