Houston is east of
Austin, west of the
Louisiana border, and south of
Dallas. The city has a total area of ; Most of Houston is on the
gulf coastal plain, and its vegetation is classified as
Western Gulf coastal grasslands while further north, it transitions into a subtropical jungle, the
Big Thicket. Much of the city was built on forested land, marshes, or swamps, and all are still visible in surrounding areas. Flat terrain and extensive greenfield development have combined to worsen flooding. Downtown stands about above sea level, and the highest point in far northwest Houston is about in elevation. The city once relied on groundwater for its needs, but land
subsidence forced the city to turn to ground-level water sources such as
Lake Houston,
Lake Conroe, and
Lake Livingston. The city owns surface water rights for of water a day in addition to a day of groundwater. Houston has four major
bayous passing through the city that accept water from the extensive drainage system. Buffalo Bayou runs through Downtown and the
Houston Ship Channel, and has three tributaries: White Oak Bayou, which runs through the Houston Heights community northwest of Downtown and then towards Downtown;
Brays Bayou, which runs along the Texas Medical Center; and
Sims Bayou, which runs through the south of Houston and Downtown Houston. The ship channel continues past Galveston and then into the Gulf of Mexico. Underpinning Houston's land surface are
unconsolidated clays, clay shales, and poorly cemented sands up to several miles deep. The region's geology developed from river deposits formed from the erosion of the
Rocky Mountains. These
sediments consist of a series of sands and clays deposited on decaying organic marine matter, that over time, transformed into oil and natural gas. Beneath the layers of sediment is a water-deposited layer of
halite, a rock salt. The porous layers were compressed over time and forced upward. As it pushed upward, the salt dragged surrounding sediments into
salt dome formations, often trapping oil and gas that seeped from the surrounding porous sands. The thick, rich, sometimes black, surface soil is suitable for rice farming in suburban outskirts where the city continues to grow. The Houston area has over 150 active
faults (estimated to be 300
active faults) with an aggregate length of up to , including the
Long Point–Eureka Heights fault system which runs through the center of the city. Land in some areas southeast of Houston is sinking because water has been pumped out of the ground for many years. It may be associated with slip along the faults; however, the slippage is slow and not considered an earthquake, where stationary faults must slip suddenly enough to create seismic waves. These faults also tend to move at a smooth rate in what is termed "
fault creep", The six original wards of Houston are the progenitors of the 11 modern-day geographically oriented
Houston City Council districts, though the city abandoned the ward system in 1905 in favor of a
commission government, and, later, the existing
mayor–council government. Locations in Houston are generally classified as either being inside or outside the
Interstate 610 loop. The "Inner Loop" encompasses a area which includes Downtown, pre–World War II residential neighborhoods and
streetcar suburbs, and newer high-density apartment and townhouse developments. Outside the loop, the city's typology is more
suburban, though many major business districts—such as
Uptown,
Westchase, and the
Energy Corridor—lie well outside the urban core. In addition to Interstate 610, two additional loop highways encircle the city:
Beltway 8, with a radius of approximately from Downtown, and
State Highway 99 (the Grand Parkway), with a radius of . Approximately 470,000 people lived within the Interstate 610 loop, while 1.65 million lived between Interstate 610 and Beltway 8 and 2.25 million lived within Harris County outside Beltway 8 in 2015. Though Houston is the largest city in the United States without formal
zoning regulations, it has developed similarly to other
Sun Belt cities because the city's land use regulations and
legal covenants have played a similar role. Regulations include mandatory lot size for single-family houses and requirements that parking be available to tenants and customers. In 1998, Houston relaxed its mandatory lot sizes from 5,000 square feet to 3,500 square feet, which spurred housing construction in the city dramatically. Such restrictions have had mixed results. Though some have blamed the city's low density,
urban sprawl, and lack of pedestrian-friendliness on these policies, others have credited the city's land use patterns with providing significant affordable housing, sparing Houston the worst effects of the
2008 real estate crisis. The city issued 42,697 building permits in 2008 and was ranked first in the list of healthiest housing markets for 2009. In 2019, home sales reached a new record of $30 billion. In referendums in 1948, 1962, and 1993, voters rejected efforts to establish separate residential and commercial land-use districts. Consequently, rather than a single central business district as the center of the city's employment, multiple districts and skylines have grown throughout the city in addition to
Downtown, which include Uptown, the
Texas Medical Center,
Midtown,
Greenway Plaza,
Memorial City, the Energy Corridor,
Westchase, and
Greenspoint.
Architecture Houston had the fifth-tallest skyline in North America (after New York City,
Chicago,
Toronto and
Miami) and 36th-tallest in the world in 2015. A seven-mile (11 km)
system of tunnels and skywalks links Downtown buildings containing shops and restaurants, enabling pedestrians to avoid summer heat and rain while walking between buildings. In the 1960s,
Downtown Houston consisted of a collection of mid-rise office structures. Downtown was on the threshold of an energy industryled boom in 1970. A succession of skyscrapers was built throughout the 1970s—many by real estate developer
Gerald D. Hines—culminating with Houston's tallest skyscraper, the 75-floor, -tall
JPMorgan Chase Tower (formerly the Texas Commerce Tower), completed in 1982. It is the tallest structure in Texas,
19th tallest building in the United States, and was previously
85th-tallest skyscraper in the world, based on highest architectural feature. In 1983, the 71-floor, -tall
Wells Fargo Plaza (formerly Allied Bank Plaza) was completed, becoming the second-tallest building in Houston and Texas. Based on highest architectural feature, it is the 21st-tallest in the United States. In 2007, Downtown had over of office space. Centered on Post Oak Boulevard and Westheimer Road, the
Uptown District boomed during the 1970s and early 1980s when a collection of midrise office buildings, hotels, and retail developments appeared along I-610 West. Uptown became one of the most prominent instances of an
edge city. The tallest building in Uptown is the 64-floor, -tall,
Philip Johnson and
John Burgee designed landmark
Williams Tower (known as the Transco Tower until 1999). At the time of construction, it was believed to be the world's tallest skyscraper outside a central business district. The new 20-story Skanska building and BBVA Compass Plaza are the newest office buildings built in Uptown after 30 years. The Uptown District is also home to buildings designed by noted architects
I. M. Pei,
César Pelli, and Philip Johnson. In the late 1990s and early 2000s, a mini-boom of midrise and highrise
residential tower construction occurred, with several over 30 stories tall. Since 2000 over 30 skyscrapers have been developed in Houston; all told, 72 high-rises tower over the city, which adds up to about 8,300 units. In 2002, Uptown had more than of office space with of
class A office space. File:Neils-Esperson Building Houston Texas.jpg|The Niels Esperson Building stood as the tallest building in Houston from 1927 to 1929. File:JP Morgan Chase Tower in Houston - Dec 2013.JPG|The
JPMorgan Chase Tower is the tallest building in Texas and the tallest 5-sided building in the world. File:Williamstower.jpg|The
Williams Tower is the tallest building in the US outside a central business district. File:Bank of America Center Houston 1.jpg|The
Bank of America Center by
Philip Johnson is an example of
postmodern architecture.
Climate after
Hurricane Harvey, August 2017 Houston's climate is classified as
humid subtropical (
Cfa in the
Köppen climate classification system), typical of the
Southern United States. While not in
Tornado Alley, like much of
Northern Texas, spring
supercell thunderstorms sometimes bring tornadoes to the area. Prevailing winds are from the south and southeast during most of the year, which bring heat and tropical moisture from the nearby Gulf of Mexico and Galveston Bay. During the summer, temperatures reach or exceed an average of 106.5 days per year, including a majority of days from June to September. Additionally, an average of 4.6 days per year reach or exceed .
Air conditioning is ubiquitous in Houston; in 1981, annual spending on electricity for interior cooling exceeded $600 million (equivalent to $ billion in ), and by the late 1990s, approximately 90% of Houston homes featured air conditioning systems. The record highest temperature recorded in Houston is at Bush Intercontinental Airport, on four occasions: September 4, 2000; August 27, 2011; and August 24 and August 27, 2023. and an event on December 7, 2017, which precipitated of snowfall. Snowfalls of at least on both December 10, 2008, and December 4, 2009, marked the first time measurable snowfall had occurred in two consecutive years in the city's recorded history. Overall, Houston has seen measurable snowfall 38 times between 1895 and 2018. On February 14 and 15, 1895, Houston received of snow, its largest snowfall from one storm on record. The coldest temperature officially recorded in Houston was on January 18, 1930. Houston generally receives ample rainfall, averaging about annually based on records between 1981 and 2010. Many parts of the city have a high risk of localized flooding due to flat topography, ubiquitous low-
permeability clay-silt prairie soils, 2016 (
"Tax Day"), and 2017 (
Hurricane Harvey). Overall, there have been more casualties and property loss from floods in Houston than in any other locality in the United States. The majority of rainfall occurs between April and October (the wet season of Southeast Texas), when the moisture from the Gulf of Mexico evaporates extensively over the city. Ground-level ozone, or smog, is Houston's predominant air pollution problem, with the
American Lung Association rating the metropolitan area's ozone level twelfth on the "Most Polluted Cities by Ozone" in 2017, after major cities such as
Los Angeles,
Phoenix,
New York City, and
Denver. The industries along the ship channel are a major cause of the city's air pollution. The rankings are in terms of peak-based standards, focusing strictly on the worst days of the year; the average ozone levels in Houston are lower than what is seen in most other areas of the country, as dominant winds ensure clean, marine air from the Gulf. Excessive man-made emissions in the Houston area led to a persistent increase of atmospheric carbon dioxide over the city. Such an increase, often regarded as "CO2 urban dome", is driven by a combination of strong emissions and stagnant atmospheric conditions. Moreover, Houston is the only metropolitan area with less than ten million citizens where such a CO2 dome can be detected by satellites. Because of Houston's
wet season and proximity to the
Gulf Coast, the city is prone to flooding from heavy rains; the most notable flooding events include
Tropical Storm Allison in 2001 and
Hurricane Harvey in 2017, along with most recent
Tropical Storm Imelda in 2019 and
Tropical Storm Beta in 2020. In response to Hurricane Harvey, Mayor Sylvester Turner of Houston initiated plans to require developers to build homes that will be less susceptible to flooding by raising them two feet above the
500-year floodplain. Hurricane Harvey damaged hundreds of thousands of homes and dumped trillions of gallons of water into the city. In places this led to feet of standing water that blocked streets and flooded homes. The Houston City Council passed this regulation in 2018 with a vote of 9–7. Had these floodplain development rules had been in place all along, it is estimated that 84% of homes in the 100-year and 500-year floodplains would have been spared damage. A nationwide developer,
Meritage Homes, bought the land and planned to develop the 500-year floodplain into 900 new residential homes. Their plan would bring in $360 million in revenue and boost city population and tax revenue. In order to meet the new floodplain regulations, the developers needed to elevate the lowest floors two feet above the 500-year floodplain, equivalent to five or six feet above the 100-year base flood elevation, and build a channel to direct stormwater runoff toward detention basins. Before Hurricane Harvey, the city had bought $10.7 million in houses in this area specifically to take them out of danger. In addition to developing new streets and single-family housing within a floodplain, a flowing flood-water stream termed a floodway runs through the development area, a most dangerous place to encounter during any future flooding event.
Harris County, like other more rural counties, cannot direct developers where to build or not build via land use controls such as a zoning ordinance by Texas law, and instead can only impose general floodplain regulations for enforcement during subdivision approvals and building permit approvals. ==Demographics==