urban
density
analysis
HOUSTON, TEXAS
Metropolitan Statistical Area
IMAGE SOURCE: Wikipedia via Wikimedia.org
!
!
Nicholas Kobel
USP 515: Urban Economics
Toulan School of Urban Studies and Planning
Portland State University
November 14, 2013
Page 1
List of tables
!
Table 1: List of counties by year incorporated into the Houston Metropolitan Statistical Area
Table 2: Population, density, and population change for Greater Houston, 1970 - 2010
Table 3: Density of Houston MSA and other geographies, 1970 - 2010
!
!
List of figures
!
Figure 1: Reference map of the Houston-The Woodlands-Sugar Land Metropolitan Statistical Area
Figure 2: Log population density of census tracts by distance from CBD, 1970 - 2010
Figure 3: Population density of census tracts by distance from CBD in Houston MSA, 1970
Figure 4: Population density of census tracts by distance from CBD in Houston MSA, 1990
Figure 5: Population density of census tracts by distance from CBD in Houston MSA, 2010
Figure 6: Map of Greater Houston MSA featuring population density, 1970 (via Social Explorer)
Figure 7: Map of Greater Houston MSA featuring population density, 1990 (via Social Explorer)
Figure 8: Map of Greater Houston MSA featuring population density, 2010 (via Social Explorer)
!
!
Page 2
Overview of Greater Houston
!
Houston-The Woodlands-Sugar Land Metropolitan Statistical Area (heretofore Greater Houston)
lies in the southeast portion of the state of Texas. Until 1971, Greater Houston consisted of
Harris and Brazoria counties. As of 2013, Greater Houston includes ten counties. Table 1
provides the year in which each county was incorporated into the MSA. !
Figure 1: Reference map of the Houston-The Woodlands-Sugar Land Metropolitan Statistical Area
A few of the most populous cities included in Houston MSA are Houston, Pasadena, Pearland,
The Woodlands, Sugar Land, Baytown, Conroe, and Galveston. As of 2010, Greater Houston has
a land area of 8,800 square miles.
!
!
!
!
!
!
!
Page 3
1950
1970
1980
1983
1993
2003
O
O
O
O
O
O
Brazoria Co.
O
O
O
O
O
Fort Bend Co.
O
O
O
O
O
Liberty Co.
O
O
O
O
O
Montgomery Co.
O
O
O
O
O
O
O
O
O
O
O
O
O
O
Harris Co.
Wallner Co.
Galveston Co.
Chambers Co.
San Jacinto Co.
O
Austin Co.
O
Table 1: List of counties by year incorporated into the Houston Metropolitan Statistical Area
Geographic and Topographical features
!
The core of Greater Houston is centered nearly 40 miles from the Gulf of Mexico. Trinity Bay,
Galveston Bay, East Bay, and West Bay carve channels inland. As an area surrounded by
temperate grassland, it considered part of the gulf coastal plains biome. This includes forests,
prairies, and swamps, which can still be seen in the area surrounding Greater Houston. The
geography is mostly low and flat, with its highest elevation at 430 feet, which has made it prone
to flooding in some areas. !
!
Central Business District (CBD)
!
The central business district of Greater Houston lies primarily in downtown Houston. For the
purposes of this analysis, the downtown census tract selected was 10001 (see Fig. 1). This district
is bound by two highways, I-10 and I-45, and further from the core is the I-610 loop. The CBD
fosters a network of pedestrian tunnels and skywalks. The CBD is home to several
headquarters, including Shell Oil, Total Petrochemicals USA, and KBR.
!
!
Population of Greater Houston
!
In 2012, Greater Houston was the fifth most populous metropolitan in the United States, with
an estimated 6.2 million people. Since 1980, Greater Houston has seen no less than a 15%
1
For 2010 Census. 1990 and 1970 Censuses identify this tract as 121.
Page 4
population increase from the previous censuses, and from 2000 to 2010, it experienced a 21%
increase in population (Table 2). Houston has also seen a significant increase in the ratio of
individuals living in the suburbs. In 1980, less than half of the population lived in the suburbs, but
by 2010, nearly 65% now live in suburbs. To frame this growth nationally, Texas and the “SunBelt” have seen tremendous growth in recent years, and Houston captures this growth.
!
Much of Greater Houston’s population growth has been auxiliary to its booming economy,
which is the fourth largest any MSA in the US. The oil, engineering, health, and manufacturing
industries have propelled Greater Houston to support the population, but the majority of
occupations are in the sectors of retail sales, cashiering, and food preparation. In 1990, Houston
saw a significant decrease in the rate of population growth. This could likely be attributed to the
fact that the international economy in industrial countries was slowed in the1980s, following the
energy crisis of the 1970s. This greatly affected the consumption of oil. Houston’s economy
depends to a large extent on this fossil fuel, which prompted a severe local recession.
!
MSA
City of Houston
Suburbs
% in Suburbs
2,201,802
1,232,407
969,395
44%
Density
-
-
-
-
% change
-
-
-
-
Population
3,148,991
1,595,138
1,553,853
49.3%
-
-
-
-
% change
’70-’80
+30.1%
+22.7%
+37.6%
+10.8%
Population
3,767,335
1,630,553
2,136,782
56.7%
530.1
3020.2
325.4
-
% change
’80-’90
+16.4%
+2.2%
+27.3%
+13.0%
Population
4,715,407
1,953,631
2,761,776
58.6%
612
3371.7
387.6
-
% change
’90-’00
+20.1%
+16.5%
+22.6%
+3.2%
Population
5,946,800
2,099,451
3,847,349
64.7%
673.7
3501.5
467.6
-
+20.7%
+6.9%
+28.2%
+9.5%
Population
1970
1980
1990
2000
2010
Density
Density
Density
Density
% change
’00-’10
Table 2: Population, density, and population change for Greater Houston, 1970 - 2010. Source: HUD.
Page 5
Density of Greater Houston
!
In stride with population growth is the increase in population density. Overall, Greater Houston
has seen an increase in population density from 1970 - 2010. However, In 1990, the proportion
of the population living in dense and highly dense census tracts (5,000 and 10,000 persons per
square mile, respectively) dropped several percentage points. This could be another effect of the
oil glut of the 1980s, whereby people could no longer afford their homes in denser
neighborhoods.
!
Year
MSA
City of Houston
CBD
% in tracts with
density >5,000
% in tracts with
density >10,000
1970
276.2
-
2,451.0
30.1%
6%
1990
421.9
3,020.2
4,593.1
25.4%
2.3%
2010
673.7
3,501.5
3,186.9
32.7%
4.3%
Table 3: Density (persons per square mile) of Houston MSA and other geographies, 1970 - 2010. Source: HUD.
Comparison of population density and distance from CBD
!
Figures 3 through 5 illustrate the population density (per square mile) by distance from the
CBD (census tract 1000) in metropolitan Houston for the years 1970, 1980, and 2010. In
comparing the change in the density gradient, there are a set of noteworthy features:
!
!
1. Distinct cities: In 1970, there were three or four prominent city centers at 28 miles, 40
miles, and 50 miles away from the CBD. Most conspicuous is the density at 50 miles,
which represents the city of Galveston. The area actually had a higher maximum density
than the core city in 1970, at 18,600 persons per square mile.
2. Engulfed cities: As time marches on, these distinct cities become consumed by the
sprawling center of Houston. In 1990, we can see remnants of the cities, and Galveston
retains its prominence, although it does experience a decrease in density. However, by
the year 2010, the cities are mostly consumed. Even once-dense Galveston shrunk to
less than 10,000 persons per square mile, and the others are hardly distinguishable.
3. Shifting urban center: The urban core in 1970 is clearly the CBD, but in 1990, and
especially in 2010, the core shifts 10 miles outward. The CBD, though a strong economic
center, does not appear to be the most inviting for residents.
Figure 2 provides each years’ density-distance relationship, expressed as a natural logarithm. It
then plots their linear regression lines and provides the corresponding functions. For each
regression formula, the y-intercept is the population density we would expect to see at the
CBD, expressed as a natural logarithm. The y-intercepts for 1970, 1990, and 2010 are 8.046,
8.579, 9.096; these correspond respectively to roughly 3100, 5300, and 8900 persons per square
mile expected to reside at the CBD. The coefficients of the formulas predict the fixed percentage
decay in population density for each additional mile x away from the CBD. Page 6
For example, suppose a tract is located 15 miles away from the CBD in 2010 (the coefficient is
-0.0652 and the y-intercept is 9.0955). We first express the coefficient as a nominal percent:
1 - e-0.0652 = 0.06312!
This means that for each additional mile x away from the CBD, we would expect to see a fixed
6.3% decrease in population density. Going further with the formula from 2010:
-0.0652 * 15 miles = -0.978!
-0.978 + 9.0955 = 8.1175!
e8.1175 = 3352.629!
Thus, at 15 miles from the CBD, we would expect to see a census tract with about 3350
persons per square mile in the year 2010, compared to about 8900 at the CBD.
!
An interesting note is the increasing R2 value as time progresses. The R2 value represents the
degree to which the variation in natural logarithm of population density can be explained by the
distance away from the CBD; thus for 2010 (where R2 = 0.041199), about 41.2% of the variation
we see in log-density among census tracts in Greater Houston is explained by their distance
from the CBD.
!
Lastly, the overall change in the trend lines suggests that Greater Houston is undergoing broadbased density growth: the urban core experiences an increase in density, while the city physically
expands toward the hinterlands. Greater Houston appears to have slowed in its physical
expansion outward from 1990 to 2010, compared to 1970 to 1990. Figure 2: Gradient of log population density by distance from CBD, 1970 - 2010. Produced in R using ggplot2 library and Adobe Illustrator.
Page 7
!
!
!
Figure 3: Population density of census tracts by
distance from CBD in Houston MSA, 1970.
Figure 4: Population density of census tracts by
distance from CBD in Houston MSA, 1990.
Figure 5: Population density of census tracts by
distance from CBD in Houston MSA, 2010.
Outset: Full spectrum of 2010 (up to 55,000
persons per square mile).
Page 8
Mapping Population density
!
The population density maps (below) for Greater Houston depict a shift in the urban core of
Greater Houston (Figure 6-8). While the most heavily populated area of the city was generally
the CBD in 1970, a southwest shift in density hub is clear in 2010. This new hub is centered
around the city of Bellaire. The observations above that a new “residential core” is forming
supports this finding. Noted in the gradient density analysis above, these maps also depict a clear
pattern of outward expansion and slight decentralization. In 1970, the metro region had a more
finite boundary, and much of Greater Houston remained in Harris County. The boundaries of
city and rural hinterlands become less pronounced in 1990 and 2010 as they begin to spread
into Brazoria and Fort Bend counties. Northeast Houston remains less dense, which is home to
several heavy industries, a quarry, and a state park. Finally, the maps also support the notion that
Galveston, a peripheral city, decreased in population density over this period of time.
!
!
Beyond the horizon
!
Many cities in the post-industrial era have seen a decline in central city population, and Greater
Houston adheres to this trend. But the amount of overall growth the city has seen in the past
40 years is tremendous. A booming oil, manufacturing, and engineering economy has helped
facilitate this growth. !
Looking back at 1990 and looking forward to 2030, I wonder if the city will experience another
decrease in the rate of growth. Petrol is a commodity societies are moving away from;
Houston’s reliance upon this industry could cause another economic downturn similar to that
experienced in1990. However, Houston’s technology industry may provide a means to
counteract this potential downturn.
Page 9
Population density
(per square mile)
!
!
!
!
!
!
Figure 6: Map of Greater Houston MSA featuring population density, 1970 (via Social Explorer).
City of Houston enlarged at right.
Population density
(per square mile)
!
!
!
!
!
!
!
Figure 7: Map of Greater Houston MSA featuring population density, 1990 (via Social Explorer).
City of Houston enlarged at right.
Figure 8: Map of Greater Houston MSA featuring population density, 2010 (via Social Explorer).
City of Houston enlarged at right.
Page 1 0