Defining Rural at the U.S. Census Bureau American Community Survey and Geography Brief
By Michael Ratcliffe, Charlynn Burd, Kelly Holder, and Alison Fields Issued December 2016 ACSGEO-1
Introduction population, from 54.4 percent in 1910 to 19.3 percent in 2010.2 Changes to settlement patterns have necessi- What image comes to mind when thinking of a rural tated periodic recalibrations in methods and definitions place? Does it include the farmhouse down the road? of what constitutes urban and rural. Does it include the new housing subdivision on the outskirts of town? Does it include the community that “Statistics have been split into urban and rural has formed at the crossroads? categories in decennial census publications for over a century.”3 The U.S. Census Bureau defines rural as what is not urban—that is, after defining individual urban areas, Geography plays a pivotal role throughout the collec- rural is what is left. Other federal agencies and tion and dissemination of data and statistics for the researchers may use a different definition of rural. For nation. For statistical measurement, it is necessary example, the U.S. Department of Agriculture’s Economic to subdivide the country into small geographic units. Research Service illustrates that there are several differ- Figure 1 shows the standard Census Bureau divisions ent ways to measure rural communities.1 of geography and their relationships. Advancements in technology, like satellite imagery and computer-based This brief highlights the history of delineating rural at mapping, have fostered new methods to collect essen- the Census Bureau, the current delineations of urban/ tial data. The innovation and technological advance- rural areas, and the relationship that exists between ments in data collection aid our ability to create a more decennial censuses, the American Community Survey nuanced, yet uniform classification of urban areas. (ACS), and geography. Additionally, the brief catego- rizes counties based on three types of rurality and The Census Bureau began identifying urban places in highlights the availability of ACS estimates. reports following the 1870, 1880, and 1890 Censuses. In the early part of the twentieth century, the Census Over the past century, the United States has experi- Bureau adopted an official definition, identifying incor- enced substantial urban growth. The suburbs around porated cities and towns with at least 2,500 people as large cities have expanded, and in many areas account urban. Population and territory outside of cities and for a large proportion of an urban area’s population towns with 2,500 or more people were considered and land area. Midsize cities and small towns have rural. Definitions evolved over this period to reflect now grown into larger urban agglomerations. As urban changing settlement patterns of the United States, but areas and their populations have increased, the rural population has declined as a percentage of the total 2 U.S. Census Bureau, 1910 to 1990 Censuses,
Figure 1. Standard Hierarchy of Census Geographic Entities
AIANNH Areas NATION (American Indian, Alaska Native, Native Hawaiian Areas)
REGIONS
ZIP Code Tabulation Areas DIVISIONS Urban Areas Core Based Statistical Areas School Districts STATES Congressional Districts Urban Growth Areas Counties State Legislative Districts
Voting Districts Public Use Microdata Areas
Traffic Analysis Zones Places County Subdivisions Census Tracts
Subminor Civil Divisions
Block Groups
Census Blocks
Source: U.S. Census Bureau, Hierarchy Diagrams,
also in response to changes in data Urban or Rural? The Census Bureau uses a users’ needs and technology.4, 5 definition based on population Deciding where to draw the line While the definition of urban has density and other measures of between urban and rural can be a continued to progress to include dense development when identi- complex task. Densely developed more people and territory in the fying urban territory. The defini- “downtowns” and sparsely popu- United States, the rural definition tion seeks to draw the boundary lated areas are relatively easy to remains as all territory, persons, around an urban area’s “footprint” identify. Where does an urban area and housing units not defined to include its developed territory. end as settlement patterns as urban.6 To accomplish this, the Census change from the city center to Bureau’s definition of urban is suburbs and beyond? The ambi- 4 Ibid. largely based on residential popu- 5 guity of the urban area’s edge is See “Differences between the Final lation density and a few other 2010 Census Urban Area Criteria and the diminished with the application Census 2000 Urban Area Criteria” available land-use characteristics to identify of standard measures. at
2 U.S. Census Bureau Starting with the 1950 Census, the Density Distance Census Bureau began implementing In order for a block to qualify The Census Bureau recognizes that criteria, through a uniform set of as urban, it must have a den- there are instances where urban objective rules, which consistently sity of 1,000 people per square development is not continuous, define urbanized areas with a pop- mile (ppsm). Using an automated but perhaps should be included in ulation of 50,000 or more. From process, qualifying blocks are a representation of an urban area. 1950 through 1990, the delineation aggregated to form a central core For example, a housing subdivision process was interactive, with geog- area. Once the initial identification may be separated from other urban raphers delineating boundaries “by process is concluded, a second development by a large regional hand” on paper maps (1950–1980) automated pass is initiated with a park, a shopping center or other or in a geographic information lower density threshold, 500 ppsm. commercial development, or even system (1990). Technological This aids in identifying blocks that a small farm. In order to accom- limitations meant that the popula- do not meet the initial density modate these real-world instances tion density-based approach was threshold, but may contain a mix in patterns of urban development, applied only to urbanized areas of residential and nonresidential hop and jump criteria are applied. with 50,000 or more people. land use (parks, schools, commer- The hop criteria allows for areas up Outside of urbanized areas, urban cial, retail, or industrial uses), and to half a mile along a road corridor was defined as places with 2,500 therefore should be included within (with multiple hops) to be included. or more people. Technological the urban area. The jump criteria allows for the advancements, increased comput- inclusion of areas up to 2.5 miles, ing power, and data processing Land use but only one jump along a road. following the 1990 Census allowed the Census Bureau to extend the Beginning in 2010, the Census Rural is defined as all population, density-based approach to smaller Bureau used land cover and imper- housing, and territory not included clusters of the population, resulting vious surfaces (paved areas, such within an urbanized area or urban in a consistent and seamless defini- as parking lots) to help identify cluster.10 As a result, the rural por- tion of urban areas with 2,500 or nonresidential urban land uses. tion of the United States encom- more people. To define an area Airports, for instance, are part of passes a wide variety of settle- as urban, the Census Bureau uses the urban landscape, but because ments, from densely settled small criteria including total population they lack population density and towns and “large-lot” housing sub- thresholds, density, land use, and tend to be located on the fringe divisions on the fringes of urban distance. Census blocks are the of developed areas, they have not areas, to more sparsely populated “building blocks” for urban areas. always been identified as a part and remote areas. Figure 2 illus- of an urban area. An airport must trates the classification process. Population thresholds have a minimum of 2,500 pas- sengers annually and be located In 2000, the Census Bureau within a half mile of other qualify- expanded the classification ing territory to be included in an 10 Details about the Census Bureau’s to include two types of urban urban area.8 A block containing urban and rural classification are available areas: urbanized areas and at
U.S. Census Bureau 3 Figure 2. Graphic Depiction of Urban/Rural Classification
Urban
Rural
Source: U.S. Census Bureau.
In 2010, there were 486 urbanized Does Rural Equal rural, and while there is overlap, areas and 3,087 urban clusters Nonmetropolitan? these geographic entities are not in the United States.11 Urbanized identical and should not be used The Census Bureau’s delineation areas contained 71.2 percent of interchangeably. of urban areas and urban clusters the population, while 9.5 percent provides the basis for the Office of were within urban clusters. The The Urban/Rural Management and Budget’s delin- rural areas of the United States Population Spectrum eation of Core Based Statistical contained 19.3 percent of the Areas or Metropolitan (metro) and By using rules for creating divisions population. Urban areas and urban Micropolitan (micro) statistical between urban and rural, it is pos- clusters (Figure 3), which contained areas.12 Metro and micro areas are sible to have peculiar outcomes the majority of the population, only nationally delineated for statisti- in the classification. Since the occupied about 3.0 percent of the cal purposes. Nonmetropolitan urban/rural classification is built land area of the country. is often used synonymously with on blocks and tracts, a county’s population can be a combination 12 See “2010 Standards for Delineating of urban and rural. A tract’s popu- Metropolitan and Micropolitan Statistical Areas” at
4 U.S. Census Bureau Figure 3. Urbanized Areas and Urban Clusters: 2010
Urbanized Areas and Urban Clusters: 2010
0 500Miles
Urbanized area Urban cluster
0 100Miles
0 100 Miles 0 50 Miles Source: U.S. Census Bureau, 2010 Census Urban Area Delineation Program.
Core Based Statistical Areas (Metropolitan and Micropolitan Areas)
The delineations of urban and rural areas are used are smaller and can be either urban or rural. Each for statistical purposes to tabulate the population metro or micro area must have one or more counties in the United States, including Puerto Rico and island containing an urban core area. Additional, adjacent areas. Additionally, the urban/rural delineation sup- counties with substantial social and economic ports the Office of Management and Budget‘s (OMB) integration to the urban core may be included. delineation of Core Based Statistical Areas (CBSAs) In the United States, there are 381 metro areas and or metropolitan (metro) and micropolitan (micro) 536 micro areas defined by OMB. Metro and micro statistical areas. Urbanized areas with 50,000 or areas account for about 94 percent of the popula- more people form the urban cores of metro areas. tion, while the remaining 6 percent is nonmetro. Urban clusters with at least 10,000 and less than The amount of land area in metro and micro areas 50,000 people form the urban cores of micro areas. is about 47 percent and the remaining 53 percent Metro and micro areas are based on counties. is nonmetro. However, the underlying geographies (urban areas and urban clusters) that are used to define CBSAs
U.S. Census Bureau 5 In this brief, we placed counties counties lives within a metro area within each rurality category and into three categories based on the (Table 1). Within the mostly urban their respective percentage of the percentage of the population that counties, 29 counties have no rural population living in rural areas. A was rural as of the 2010 Census.13 population, meaning the counties wide range of population crosses The three rurality categories are: are 100 percent urban. According each grouping. For example, com- (1) completely rural, (2) mostly to the 2010 Census, these 100 pletely rural counties range from rural, and (3) mostly urban.14 Using percent urban counties comprised 82 people in Loving County, TX, to the 2010 urban/rural definition, about 3.5 percent of the total more than 34,000 people in Lincoln there are 704 counties or county U.S. population. When combined, County, ME. Stanley County, SD, statistical equivalents that are the 1,253 mostly urban counties provides a good example of the 100 percent or completely rural. contained about 266.6 million complicated nature of classifying These counties have no areas that people or 86.3 percent of the total counties as either mostly urban are identified as urban and are U.S. population in 2010.15 or mostly rural. Stanley County home to less than 2.0 percent of had a population of nearly 3,000, Counties were sorted based on the total U.S. population. Over with 2,078 people residing in Fort the proportion of the population 20 percent of the population liv- Pierre, SD, the county’s largest pop- living in an urban or rural area ing in these 704 completely rural ulation center. Fort Pierre is located in 2010. Table 2 shows the five across the Missouri River from most and least populous counties 13 This includes the United States only, not Pierre, SD, and is included in the Puerto Rico. Pierre urban cluster, which had a 14 Completely rural counties have a 15 There were 1,253 mostly urban coun- population that is 100 percent rural. Mostly ties in the 2011–2015 ACS 5-year estimates, total population of 14,425 in 2010. rural counties have a population that is but 1,254 mostly urban counties in the 2010 With 57.5 percent of its population 50.0–99.9 percent rural. Mostly urban Census. The statistics for Urban/rural split counties have a population that is less and metro/nonmetro split in Table 1 use data defined as urban, Stanley County is than 50.0 percent rural. from the 2011–2015 ACS.
Table 1. County Type by Percentage of Urban/Rural and Metro/Nonmetro Urban/rural split Metro/nonmetro split Type of county Number of Percent of total Percent Percent Percent Percent counties1 population urban rural metro nonmetro2 Mostly urban...... 1,253 86 .3 89 .0 11 .0 93 .9 6 .1 Mostly rural...... 1,185 11 .9 33 .1 66 .9 31 .3 68 .7 Completely rural ...... 704 1 .7 0 .0 100 .0 20 .2 79 .8 1 Number of counties or county statistical equivalents are based on 2011–2015 American Community Survey 5-year estimates . In 2013, Bedford city, VA, changed to town status and was added to Bedford County, decreasing the total number of mostly urban counties to 1,253 . 2 Nonmetro includes micropolitan areas . Sources: U .S . Census Bureau, 2010 Census and 2011–2015 American Community Survey 5-year estimates .
Table 2. Selected Most and Least Populous Counties by Rurality: 2010 Completely rural Mostly rural Mostly urban Less 100 50–99 than 50 County County County 2010 percent 2010 percent 2010 percent Census rural Census rural Census rural Most Lincoln County, ME. . . . . 34,457 100 .0 York County, ME ...... 197,131 56 .8 Los Angeles County, CA. . . 9,818,605 0 .6 populous Accomack County, VA. . . . 33,164 100 .0 Johnston County, NC. . . 168,878 52 .0 Cook County, IL...... 5,194,675 0 .0 Cass County, MN. . . . . 28,567 100 .0 Penobscot County, ME . . . 153,923 57 .7 Harris County, TX ...... 4,092,459 1 .2 Cherokee County, NC. . . . 27,444 100 .0 Merrimack County, NH. . 146,445 54 .6 Maricopa County, AZ. . . . . 3,817,117 2 .4 San Jacinto County, TX. . . 26,384 100 .0 Randolph County, NC. . . . 141,752 56 .2 San Diego County, CA. . . 3,095,313 3 .3 Least Arthur County, NE. . . . . 460 100 .0 Dewey County, SD. . . . 5,301 64 .1 Hemphill County, TX . . . . . 3,807 27 0. populous Kenedy County, TX . . . . . 416 100 .0 Storey County, NV. . . . . 4,010 92 .6 Crockett County, TX. . . . . 3,719 22 7. King County, TX...... 286 100 .0 Sierra County, CA. . . . . 3,240 99 .7 Kinney County, TX...... 3,598 20 5. Kalawao County, HI. . . . . 90 100 .0 Ziebach County, SD. . . . 2,801 73 .5 Reagan County, TX. . . . . 3,367 13 3. Loving County, TX. . . . . 82 100 .0 Quitman County, GA. . . . 2,513 73 .1 Stanley County, SD. . . . . 2,966 42 5. Source: U .S . Census Bureau, 2010 Census .
6 U.S. Census Bureau classified as mostly urban for this Table 3. 5-year ACS file, data are pooled analysis, however, nearly all of the Geographic Relationship and reweighted to the last year. county’s land area (99.9 percent) Between the Decennial As such, the most recent geogra- is rural. Stanley County is in the Census and 1-Year ACS for phy is applied to the entire 5-year mostly urban category with large Urban/Rural Areas file.17 It is recommended that data metro counties, such as San Diego, users interested in urban/rural Census year CA; Los Angeles, CA; and Cook, IL ACS 1-year data only compare nonoverlap- 2000 2010 (Chicago). Stanley County provides ping ACS 5-year datasets using the 2005 ...... X a good example of the challenges 2006 ...... X same definition of urban and rural. of classifying counties based only 2007 ...... X For example, the 2008–2012 ACS on the percentage of a county’s 2008 ...... X 5-year estimates and 2013–2017 2009 ...... X population that is rural. 2010 ...... X ACS 5-year estimates will be the 2011 ...... X first nonoverlapping datasets that Relating the Urban/Rural 2012 ...... X use the same 2010 urban/rural Definition to the American 2013 ...... X 2014 ...... X definitions. Community Survey 2015 ...... X Unlike ACS 1-year estimates that The definitions of urban and rural Source: U .S . Census Bureau, American provide data for about one quarter are updated every decade following Community Survey, Geographic Boundaries by Year,
Source: U .S . Census Bureau, American Community Survey .
U.S. Census Bureau 7 Additional Information American Community included in this report. All compar- Survey ative statements in this report have Urban and rural classification undergone statistical testing, and The American Community Survey comparisons are significant at the www.census.gov/geo/reference (ACS) is a nationwide survey 90 percent confidence level unless /urban-rural.html designed to provide communities otherwise noted. In addition to with reliable and timely demo- www.census.gov/geo/reference sampling error, nonsampling error graphic, social, economic, and /ua/urban-rural-2010.html may be introduced during any of housing data for the nation, states, the operations used to collect and www.census.gov/geo/reference congressional districts, counties, process survey data such as edit- /ua/uafaq.html places, and other localities every ing, reviewing, or keying data from year. It has an annual sample size questionnaires. For more informa- 2010 Census of about 3.5 million addresses tion on sampling and estimation across the United States and Puerto Information on other population methods, confidentiality protection, Rico and includes both housing and housing topics is presented and sampling and nonsampling units and group quarters (e.g., in the 2010 Census Briefs series errors, please see the ACS Multiyear nursing facilities, college dormito- located on the Census Bureau’s Web Accuracy of the Data document ries, and prisons). The 5-year file of site at
8 U.S. Census Bureau