Devine concluded by identify- areas required a labor-intensive, interactive paper
ing key points for the upcom- map–based process that involved some amount
ing evaluations. These include of subjectivity (e.g., in deciding whether a nearby
focusing on the most promis- densely settled area was part of a UA). The inclusion
ing alternatives, using produc- of nearby areas often requires the use of “jumps” or
tion requirements and underly- “hops” over unsettled or less-dense areas. Although
ing principles to guide decisions, whimsical sounding, these are technical terms, with
providing the most comprehen- jumps generally limited to a single jump (in a given
sive evaluation possible with lim- direction) of no more than 1.5 miles, but hops per-
ited resources, and providing data mitting multiple spans of up to 2.5 miles.
sets that will allow others to assess the For 1990, the U.S. Census Bureau published
accuracy of the estimates. UA criteria in a Federal Register notice for the first
time and used interactive delineation software. The
Developing Criteria for
process was more automated, but still required
Delineating Urban Areas subjectivity—as in the application of hops, which
Michael Ratcliffe of the U.S. Census Bureau stressed
were first used in 1990. For 2000, the UA concept
that his presentation would not describe proposed
was supplemented with urban clusters (UCs)—the
criteria, but rather ideas to generate feedback for use
same concept, but applied to smaller areas. UAs
in preparing proposed criteria for the definition of
have populations of 50,000 or more, and UCs have
urban areas. He noted that the U.S. Census Bureau
populations of 2,500–50,000.
has officially defined urban areas since 1910, that
Ratcliffe described how the use of automated
they define urban areas after each census, and that
software has shifted the focus from which areas to
the areas are defined for statistical—not program-
include in UAs to questions of where to split large
matic—purposes. The criteria are reviewed and
urban areas. If fully automated, the process would
revised before each census, but a common theme
possibly split urban areas in the middle of a down-
over the decades has been to identify the built-
town business district or identify a single continu-
up, densely settled urban landscape. The popula-
ous UA from Wilmington, Delaware, to Springfield,
tion threshold of 2,500 is an enduring part of the
Massachusetts—and, by rule, call it New York.
changing definitions.
Issues for 2010 include identifying nonresiden-
Adopted in 1950, the density-based urbanized
tial urban land uses on the fringe of UAs, establishing
area (UA) concept allowed for the inclusion of more
objective methods for splitting large urban agglom-
than just incorporated areas, and even noncontigu-
erations, comprehensively identifying undevelop-
ous areas. The UA concept was largely unchanged
able territory (e.g., wetlands and steep slopes), and
over the following decades, and the delineation of
delineating UAs in Puerto Rico and the island areas.
Looking beyond 2010, a challenge will be how to
incorporate annual data from the ACS and the pos-
sible definition of “suburban” and “exurban” areas.
Chris Henrie of the U.S. Census Bureau rein-
forced two major points: the continued use of the
2,500 population threshold and the fact that the
threshold no longer relates to incorporated areas.
Stats Program Highlighted
Henrie then filled in with helpful details about the
application of jumps and hops, the exemption of
areas such as parks, and other issues in the inclusion/
in US Airways Magazine
exclusion of discontiguous areas. He also described
options being explored, including the greater use
In the July issue of US Airways magazine, the article profiling Roanoke,
of census tracts (allowing for greater use of com-
Virginia, “Key to the City of Roanoke,” highlighted a new statistical
muting data) and the use of data on impervious
program soon to be unveiled at Roanoke College in Salem. This new
(paved) land surfaces and steep slopes. The bureau
introductory-level statistics class will use statistical analysis to “examine
is also reconsidering the importance of the concept
the effect of gun control on mortality rates, analyze the latest health
of the central place to the realistic delineation of
fads, or even predict the weather.” According to the article, Roanoke
urban areas. Above all, Henrie stressed that the U.S.
is one of the only colleges in the nation to offer this approach to core
Census Bureau remains committed to an objective,
curriculum. The entire article can be found at www.usairwaysmag.com/
equitable, and consistent nationwide delineation of
city_profiles/city/roanoke_virginia. n
urban areas. n
18 AmstAt News AUGUST 2009
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