Overview
The ERS Commuting Zones (CZs) and Labor Market Areas (LMAs) were
first developed in the 1980s as ways to better delineate local
economies. County boundaries are not always adequate confines for a
local economy and often reflect political boundaries rather than an
area's local economy. CZs and LMAs are geographic units of analysis
intended to more closely reflect the local economy where people
live and work. Beginning in 1980 and continuing through 2000,
hierarchical cluster analysis was used along with the Census
Bureau's journey to work data to group counties into these areas.
In 2000, there were 709 CZs delineated for the U.S., 741 in 1990,
and 768 in 1980. LMAs are similar to CZs except that they had to
have a minimum population of 100,000 persons. LMAs were only
estimated in 1980 and 1990. This was done in order for the Census
Bureau to create microdata samples using decennial census data
(1980 PUMS-D, 1990 PUMS-L) that avoided disclosure. The LMAs were
discontinued in 2000 because researchers found them to be too large
and not as useful as the CZs. The identical methodology was used to
develop CZs for all three decades.
An update of the Commuting Zones is planned for 2014.