Vital Signs: Greenfield Development – Bay Area shapefile

VITAL SIGNS INDICATOR
Greenfield Development (LU5)

FULL MEASURE NAME
The acres of construction on previously undeveloped land

LAST UPDATED
November 2019

DESCRIPTION
Greenfield development refers to construction on previously undeveloped land and the corresponding expansion of our region’s developed footprint, which includes the extent of urban and built-up lands. The footprint is defined as land occupied by structures, with a building density of at least 1 unit to 1.5 acres.

DATA SOURCE
Department of Conservation: Farmland Mapping and Monitoring Program
GIS Data Tables/Layers (1990-2016)
https://www.conservation.ca.gov/dlrp/fmmp

U.S. Census Bureau: Decennial Census
Population by Census Block Group (2000-2010)
http://factfinder.census.gov

U.S. Census Bureau: American Community Survey (5-year)
Population by Census Block Group (2000-2017)
http://factfinder.census.gov

METHODOLOGY NOTES (across all datasets for this indicator)
For regional and local data, FMMP maps the extent of “urban and built-up” lands, which generally reflect the developed urban footprint of the region. The footprint is defined as land occupied by structures with building density of at least 1 unit to 1.5 acres. Uses include residential, industrial, commercial, construction, institutional, public administration, railroad and other transportation yards, cemeteries, airports, golf courses, sanitary landfills, sewage treatment, water control structures, and other developed purposes.

To determine the amount of greenfield development (in acres) occurring in a given two-year period, the differences in urban footprint are computed on a county-level. FMMP makes slight refinements to urban boundaries over time, so changes in urban footprint +/- 100 acres are not regionally significant. The GIS shapefile represents the 2016 urban footprint and thus does not show previously urbanized land outside of the footprint (i.e. Hamilton Air Force Base).

For metro comparisons, a different methodology had to be used to avoid the geospatial limitations associated with FMMP. U.S. Census population by census block group was gathered for each metro area for 2000, 2010, and 2017. Population data for years 2000 and 2010 come from the Decennial Census while data for 2018 comes from the 2017 5-year American Community Survey. The block group was considered urbanized if its average/gross density was greater than 1 housing unit per acre (a slightly higher threshold than FMMP uses for its definition). Because a block group cannot be flagged as partially urbanized, and non-residential uses are not fully captured, the urban footprint of the region calculated with this methodology is smaller than in FMMP. The metro data should be primarily used for looking at comparative growth rate in greenfield development rather than the acreage totals themselves.