Urbanization of the United States over two centuries: an approach based on a long-term database (1790–2010)

Abstract

This paper presents an original methodology for the construction of a harmonized database for urban areas in the United States from 1790 to 2010 (a period with a census every 10 years, amounting to 23 dates). Upstream, this method is based on a theoretical choice, the use of a spatio-temporal reference frame to construct urban areas over the long term, defined by a maximum range of one hour’s travel for each period. We used an automatic aggregation from a Reilly model. Urban measures (growth, concentration) derived from this harmonized database are then presented, providing a unified picture of urbanization in the United States over more than two centuries. They are compared with results derived from more classical databases established using the official figures from the Census Bureau, or from other constructions differing from the present system. The results diverge considerably in some instances, which confirms the impact of the method of delineation of geographical areas in measures of growth.

Keywords:

• urban area
• harmonized database
• time–space reference frame
• Reilly model, GIS

Acknowledgments

This research was supported by the French National Research Agency (ANR Corpus et Outils de la Recherche en SHS, Harmonie-Cités) and the European Research Council (ERC GeoDiverCity). We acknowledge feedbacks from reviewers, which improved the manuscript.

Notes

1. This difference is due to the fact that the one-hour time-budget is considered as an average, computed for the whole population of the city, whereas in our work we aim to delineate the maximum radius of the city that integrates the most remote suburbs.

2. The micropolitan areas are defined by the Census Board in 2000 around urban clusters, with a minimal commuting threshold identical to that of the metropolitan areas, that is, 25%. The metropolitan areas are defined around urbanized areas.

3. The year is called ‘1940’ for functional urban areas delineated by the one-hour isochron and ‘1941’ for metropolitan areas. The definition of metropolitan areas was created in 1949 by the Census Bureau but we used the work by D. Bogue (1953), which extrapolated SMA backwards on the basis of their 1950 boundaries.

4. The minimum threshold adopted in this first database was 10,000 from 1870.

5. The change from a place to a municipality occurred by way of an ‘act of incorporation’. The vote of the majority in favor of incorporation led to the establishment of a local authority, creating a city, a town, a village, or a borough.

6. The selection criteria were based on the population (level at the considered date and previous trajectory) and the status (urban, rural) given in the 1930 census that depended on a minimal density threshold.

7. The consolidation process means that two different legal entities merge to form a new one.

8. A territory is a political division that is directly under the supervision of the federal government.

9. The application was developed in Python language and is compatible with ArcGIS. A graphical user interface enables entering the values of parameters and the visualization of the connected components obtained.

10. The main sources are detailed in the online supplementary material.

11. These were Baltimore, Boston, Buffalo, Chicago, Cleveland, Detroit, Los Angeles, Milwaukee, New York, Philadelphia, Pittsburgh, San Francisco, and Saint-Louis. The main part of this documentation is detailed in the online supplementary material.

12. The urbanized areas concern the 157 municipalities larger than 50,000 inhabitants. The criteria used were based on statistical parameters (density, population) and on a morphological approach: the boundaries had to follow the main features of urban landscapes such as roads, streets, railroads, or rivers.

13. Brian Berry evokes the ‘reassertion of fundamental predispositions of the American culture that, because they are antithetical to urban concentration, have resulted in many of the contradictions and conflicts of recent decades’ (1976, p. 24).

Additional information

Funding

This work was supported by the ANR Harmonie-cités 2008–2012, ERC GeoDiverCity 2011–2015.