Two centuries of settlement and urban development in the United States

Abstract

Over the past 200 years, the population of the United States grew more than 40-fold. The resulting development of the built environment has had a profound impact on the regional economic, demographic, and environmental structure of North America. Unfortunately, constraints on data availability limit opportunities to study long-term development patterns and how population growth relates to land-use change. Using hundreds of millions of property records, we undertake the finest-resolution analysis to date, in space and time, of urbanization patterns from 1810 to 2015. Temporally consistent metrics reveal distinct long-term urban development patterns characterizing processes such as settlement expansion and densification at fine granularity. Furthermore, we demonstrate that these settlement measures are robust proxies for population throughout the record and thus potential surrogates for estimating population changes at fine scales. These new insights and data vastly expand opportunities to study land use, population change, and urbanization over the past two centuries.

Fig. 1. Maps of the FBUY at different levels of granularity.

The maps depict national-, regional-, and local-scale processes of human development: (A) county-level FBUY within contemporary (Census 2010) boundaries used as constant units of analysis over time (counties where no built-up year is available are shown in gray); more detailed distributions of FBUY for the states of Colorado, Kansas, and Ohio within (B) county boundaries, (C) 2500-m grid cells, and (D) 250-m grid cells, respectively. (E) A detailed depiction of the 250-m resolution data for the cities of Denver, CO; Wichita Falls, KS; and Columbus, OH.

Fig. 2. HISDAC-US settlement layers derived from the ZTRAX data at fine granularity for different points in time.

The layers are shown at 250-m spatial resolution for different points in time, 1810–2010, for Rockingham County, NH and surroundings, including: (A) FBUY layer in which raster cells are assigned the earliest built year recorded, and a time series of the number of built-up property records (BUILD) located within a raster cell in (B) 1810, (C) 1860, (D) 1910, (E) 1960, and (F) 2010. County boundaries of the 2010 census are shown in black.

Fig. 3. Settlement trends and multitemporal distributions for San Francisco, Atlanta, and Boston.

(A) Time series of densification and expansion, calculated over 15-year time increments computed within metropolitan statistical area boundaries of 2010. (B) New built-up grid cells (indicated by black grid cells) during the given time periods. (C) Change in BUI (i.e., the sum of building indoor area per grid cell) during the given time periods, with warmer colors indicating greater change.

Fig. 4. Settlement trends describing different types of growth in rural and urban strata.

Boxplots of semi-decadal distributions of (A) densification and (B) absolute expansion in rural and urban counties. (C) Graphic display of relative locations of newly and previously built-up grid cells to calculate midrange expansion, internal, and peripheral growth within the Greater Washington, DC area including Arlington, Bethesda, and Georgetown. (D) Trends of building indoor area (BIA) in urban and rural strata (counties), each broken down into whether the increase happened in newly built-up cells (midrange expansion), in previously built-up cells at the edge of larger BUAs (peripheral growth), or in previously built-up cells in inner parts of BUAs (internal growth). (E) Proportion of internal, peripheral, and internal-peripheral combined growth (i.e., growth in previously built-up cells) in relation to overall change for the two strata (rural and urban).

Fig. 5. Correlation measures between county-level population counts and settlement variables.

The different plots show correlations over the time period from 1810 to 2010 between population and (A) the number of built-up property records (BUILD), (B) BUI, and (C) BUA. avg. corr., average correlation. In (D), correlation measures between county-level population change and absolute expansion (Abs. expansion) are shown for the same time period. Population counts are enumerated within historical county boundaries, while settlement measures (all land use classes) are calculated within contemporary county boundaries. Correlation measures are shown for various levels of temporal county boundary stability (e.g., the blue lines represent only counties whose area did not change more than 10% over time) to demonstrate the importance of compatible spatial units in spatiotemporal analysis. Average correlation coefficients are shown over all years in parentheses.