Greenfield Development

Where is open space being converted to development?

Greenfield Development

Greenfield development refers to the change in the extent of urban and built-up lands, which taken together comprise the developed footprint of the region. The footprint is defined as land occupied by structures, with a building density of at least 1 unit to 1.5 acres.

From the days of the first Native American settlements, human activity in the Bay Area clustered around the San Francisco Bay. With the passage of time, development of the region’s 7,000 square miles of land has spread inland from the Bay, and this trend accelerated markedly during the rapid economic expansion that followed World War II.

As this process of development claimed lands formerly reserved for other uses, Bay Area residents have come to regard undeveloped lands as a precious resource – and not only for their scenic value. Construction on undeveloped lands – referred to as greenfield - decreases the area of agricultural lands and increases the amount of impervious surfaces. The loss of greenfield across the Bay Area also tends to correlate with an increase in the overall number of vehicle miles driven, as the people who settle on the newly developed lands often have to travel long distances to work.

Regional Performance
The pace of Bay Area greenfield development slowed by nearly a third from 2000 to 2012.

The amount of greenfield land developed in the Bay Area from 2000 to 2012 is 32 percent less than the acreage developed during the final decade of the last century. Expansion of the Bay Area’s developed acreage in the final two years of this stretch – from 2010 to 2012 – was the smallest of any two-year period since 1990. This was no doubt influenced by the lingering effects of the Great Recession, but may also reflect the trend away from greenfield development as well as the growth management strategies established by cities and counties across our region.

Development across the Bay Area from 2000 to 2012 increased the size of the region’s developed area to approximately 787,000 acres, making it 13 percent larger than the footprint of 1990. Since 1990, greenfield development was greatest between 1990 and 2000, when approximately 55,000 acres were added to the region’s developed area. Nevertheless, overall densification increased in the 1990’s because while the addition of the newly developed acreage boosted the size of the developed Bay Area by 8 percent, population grew by 12 percent.

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Regional Distribution
Brentwood and Contra Costa County led the region in number and percentage of acres converted to developed land from 2000 to 2010.

The city of Brentwood, located in eastern Contra Costa County, developed the largest amount of greenfield land in the first 12 years of the century as a result of significant housing development. Brentwood saw the development of close to 2,700 formerly agricultural acres – well above the 1,800 acres converted in San Jose, the city with the second-highest total. Nearby, the fast-growing Solano County cities of Fairfield and Vacaville each experienced greenfield development of more than 1,000 acres during this period.

Local Focus
The developed area of the region grew in large part due to activity in eastern Contra Costa and southern Santa Clara counties.

Powered in part by the significant development activity in Brentwood and the neighboring cities of Antioch and Oakley, a significant chunk of the greenfield development over the two-decade time period from 1990 to 2010 occurred in Contra Costa County. The county’s 22,600 acres represent 25 percent of the regional acreage converted to developed land during the period. Add in the greenfield development in Santa Clara County, and the two counties together account for more than 40 percent of our region’s greenfield acreage developed in that 20-year timeframe. The vast majority of Santa Clara County’s greenfield development occurred in San Jose, followed by Gilroy, unincorporated county lands, and Morgan Hill.

Greenfield Development Since 1990

Year: 2012

Click on an area of the map to see when it was developed.
Developed before 1990
Developed in the 1990s
Developed in the 2000s
Developed in the 2010s
National Context
The Bay Area consumed the fewest greenfield acres among the top 10 metro areas in the last decade.

While the fast-growing Sunbelt metropolitan regions of Atlanta, Dallas and Houston absorbed land at a prodigious pace from 2000-2010 – with each expanding its urban footprint by more than 30 percent – the acreage of developed land in the Bay Area expanded by less than 10 percent (measured in terms of U.S. Census block groups). Indeed, during this period, the Bay Area’s developed land grew by the smallest number of acres and the third-smallest percentage of any of the nation’s 10 largest metro areas. Only New York City and Los Angeles also registered greenfield-development percentages in the single digits.


Department of Conservation: Farmland Mapping and Monitoring Program

GIS Data Tables/Layers (1990-2012)

U.S. Census Bureau: Population Data

Population by Census Block Group (2000-2010)

Image: Flickr (Creative Commons license), Photographer: Pembina Institute, 2994480730_4fbebc392f_o.jpg

Methodology Notes: 

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 2-year period, the differences in urban footprint GIS layers are computed on a county and city level. FMMP makes slight refinements to urban boundaries over time, so changes in urban footprint +/- 100 acres are not regionally significant. Reductions in a city’s urban footprint is often due to these refinements, although the creation of new parks or open space on previously developed is also a potential cause.

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 and 2010. 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.