UrbanizedAreaGrowth


 * Indicators**:: Population Trends :: Urbanized Area Growth :: Land Cover Change

=Urbanized Area Growth=


 * What is this?**

Urbanized areas are defined by the US Census Bureau ( see inset) to include the most densely populated areas of the nation. The Triangle contains two urbanized areas – Raleigh and Durham – that have been growing through time and covered almost 15% of the Triangle in 2000 (Figure 1, 2).

**Figure 1.** Urbanized Areas in the Triangle, 1950-2000. Source: US Census Bureau.


 * **// Urbanized Area //**

The US Census Bureau defines an urbanized area as one or more “central places” with a population density of at least 1,000 people per square mile, and the surrounding densely settled territory. Raleigh and Durham were the central places in the Triangle until 1970. In 2000, the Durham Urbanized Area was expanded to include Carrboro, Chapel Hill, and Hillsborough, and the Raleigh Urbanize Area was expanded to include Apex, Cary, Fuquay-Varina, Garner, Holly Springs, Knightdale, Morrisville, Rolesville, Wake Forest, and Youngsville.  Urbanized area boundaries are likely to change again for the 2010 census. ||


 * Why is this important?**

As urbanized areas grow, land is transformed from forests and fields to business, homes, and roads, changing in unknown ways (but presumably decreasing) the level of public benefits provided by forests and fields.


 * What does this measure show?**

Urbanized areas grew markedly between 1950 and 2000, from less that 1% of the Triangle to almost 15% (Figure 2).

The area of land in the Triangle's urbanized areas increased 1,658% between 1950 and 2000, which is 3.4 times the population increase (484%) (Table 1). Thus, population density in our urbanized areas has decreased dramatically from 5,244 to 1,741 people per square mile, a 67% reduction. Stated another way, our footprint in these urbanized areas has more than tripled during this period – from 0.12 acres per person in 1950 to 0.37 acres per person in 2000 (Figure 3).

This means that we are devoting more land per person to businesses, homes, and roads in our urbanized area than ever before – this is one measure of the phenomenon often called //sprawl//. The Raleigh Urbanized Area has grown more than the Durham Urbanized Area, in both land area and population (Table 1). Had we continued to develop at 1950 densities, Urbanized Areas would have occupied less than 5% of the Triangle in 2000.
 * [[image:%UA.jpg width="450" height="364"]] || [[image:AcresPerPerson.jpg width="450" height="364"]] ||
 * **Figure 2.** Proportion (%) of Triangle defined as Urbanized Area. Source: US Census Bureau || **Figure 3.** Increasing footprint of people living in Urbanized Areas, as measured by acres developed per person. Source: US Census Bureau ||


 * Table 1. ** Triange Urbanized Area and population, 1950-2000. Source: US Census Bureau.


 * Limitations**

The latest data are 10 years old - 2010 US Census data are not yet available.


 * Author** George Hess, NC State University :: 2010 April 6


 * Technical Notes**

Urbanized Area populations and area were obtained from:
 * 1950, 1970-1990 from Ben Hitchings, Triangle J Council of Governments, on 1999 Nov 12 when preparing Triangle Land Conservancy's //State of Open Space 2000// report
 * 1960 was obtained from Ryan Short, US Census Bureau, on 1999 Nov 12
 * 2000 data were obtained from Paul Black, Triangle J Council of Governments, on 2010 Feb 3
 * Data for creating map were obtained from Ben Bearden, Triangle J Council of Governments, on 2010 Mar 8

When calculating percentage of area, we used 3,322 sq-miles for the total area of the Triangle, as documented in Triangle Land Conservancy's //State of Open Space 2000//.

Here is the spreadsheet containing the data: [|PopUrbanizedArea.xlsx] Here are the geographic information system layers used for the map (zipped Arc files): [|TJCOGHistoricUA.zip]


 * Indicators**:: Population Trends :: Urbanized Area Growth :: Land Cover Change