Employment Centers are identified as areas with a high concentration of employment based on SANDAG’s 2016 employment inventory from Urbansim summarized to quarter-mile radius hexagons. Local-maxima were identified as starting points, and regions were grown to include neighboring hexagons meeting a minimum employment density threshold within an approximate 2-mile radius. The resulting boundaries were generalized (taking into account major barrier features such as topography and freeways) and used to select SANDAG Master Geographic Reference Areas (MGRAs) by activity-weighted (population and employment) centroid. Employment centers are ranked by Tier based on total number of jobs:
Tier 1: 50,000 or more jobs
Tier 2: 25,000 to 49,999 jobs
Tier 3: 15,000 to 24,999 jobs
Tier 4: 2,500 to 14,999 jobs
Hexbin geography (where people live map layers) – generated using a quarter-mile radius hex bin grid overlay on the region. Data is summarized by hex bin spatially using the centroid of an overlying geography.
Where people live by Employment Center they Work In –2015 LEHD census block level data; converted to hexbin (see hexbin geography). LEHD data was used as it contains information on both the home and work location. Data represents an employee residence by the employment center they work in.
https://lehd.ces.census.gov/data/.
