Harris County Texas map
29.86° N · 95.39° W · County seat: Houston · 1,777 sq mi · Central Time
Harris County counted 4,731,145 people in 2020 — more than 25 states — which makes it the most populous county in Texas and the third-most populous in the United States. It is built on flat coastal prairie drained by a web of bayous, and the whole shape of it comes from one of them: Buffalo Bayou, dredged into the Houston Ship Channel so that ocean ships could reach a city 50 miles inland.
Centered north of downtown Houston. I-610 makes the inner loop, Beltway 8 the middle ring and SH-99 the outer arc; the Ship Channel runs east from downtown to Galveston Bay.
Where Harris County is
Harris is one of the original 23 counties of the Republic of Texas, created in December 1836 and organized the following March. It was called Harrisburg County until 1839, after the town John Richardson Harris laid out on Buffalo Bayou in 1826; the county kept his surname when the name was shortened. Its seat, Houston, took the ground just upstream at the head of navigation.
Seven counties touch it. Montgomery is north, Liberty northeast, Chambers and Galveston southeast across the bay, Brazoria south, Fort Bend southwest and Waller northwest. The southeast corner opens onto Galveston Bay rather than another county line, which is the county's only water frontage of consequence — 70 of its 1,777 square miles are water.
Nothing here is far from anything else by Texas standards. Pasadena sits 16 miles southeast of the county's center, Sugar Land 22 miles southwest over the Fort Bend line, The Woodlands 22 miles north in Montgomery County and Galveston 52 miles southeast at the end of I-45. The county's land area is larger than the state of Rhode Island.
Cities and towns
Populations below are the 2020 census count for the part of each place inside Harris County; several cities cross a county line. A large share of the county's residents live in unincorporated territory that belongs to no city at all, which is why Harris County government runs so much of the road, park and law-enforcement work here.
| Place | Type | 2020 population |
|---|---|---|
| Houston (part) | City · county seat | 2,252,020 |
| Pasadena | City | 151,950 |
| Baytown (part) | City | 80,739 |
| La Porte | City | 35,128 |
| Deer Park | City | 34,500 |
| Bellaire | City | 17,201 |
| Humble | City | 16,787 |
| South Houston | City | 16,162 |
| West University Place | City | 15,038 |
| Seabrook (part) | City | 13,628 |
| Webster | City | 12,488 |
| Tomball (part) | City | 12,324 |
| Katy (part) | City | 11,802 |
| Galena Park | City | 10,738 |
Bellaire and West University Place are separate cities entirely surrounded by Houston, which is why the map shows two small squares inside Loop 610.
The rings and the radials
Harris County road geography is three concentric rings crossed by six radial freeways. The rings were built outward in roughly thirty-year steps, and each one marks where the built-up edge stood when it opened.
- I-610 (the Loop) – the inner ring around Houston proper, passing the Astrodome and NRG Park on the south, the Galleria on the west and the Ship Channel industry on the east.
- Beltway 8 / Sam Houston Tollway – the middle ring, roughly 10 miles out, with a free frontage road beside the tolled main lanes and the Ship Channel tunnel under the water at Baytown's west side.
- SH-99, the Grand Parkway – the outer arc, built in segments across Katy, Cypress, Spring and the Lake Houston side, and continuing into Fort Bend, Montgomery, Liberty and Chambers counties.
- I-45 – the north–south spine: Conroe and Dallas to the north, downtown, then southeast past Hobby Airport to League City and Galveston.
- I-10 (Katy Freeway east, East Freeway west) – San Antonio and Katy to the west, Baytown, Beaumont and Louisiana to the east.
- I-69 / US-59 – the Southwest Freeway toward Sugar Land and Victoria, the Eastex Freeway toward Humble, Cleveland and Lufkin.
- US-290 (Northwest Freeway) – northwest through Jersey Village and Cypress toward Hempstead and Austin.
- US-90 and SH-3 – the older parallel routes through Crosby and along the rail line to Galveston, both largely replaced by the interstates beside them.
- SH-6 and SH-146 – the arterial through Katy and Missouri City, and the bay-side route from Seabrook over the Fred Hartman Bridge into Baytown.
Buffalo Bayou and the Houston Ship Channel
Buffalo Bayou enters from the west, runs through the Memorial and downtown reaches, and meets White Oak Bayou at Allen's Landing — the spot where Houston's founders sold the town in 1836 as a port. It was a shallow, snag-filled stream. Repeated dredging turned the lower bayou and the upper end of Galveston Bay into the Houston Ship Channel, opened with ceremony in November 1914 and deepened many times since.
The channel is the county's industrial axis. From the Turning Basin east of downtown it runs past Galena Park, Jacinto City, Pasadena, Deer Park, La Porte and Baytown before reaching open water, and the refineries, petrochemical plants and container terminals along both banks make Port Houston one of the busiest ports in the United States by tonnage. The Lynchburg Ferry still crosses the channel free of charge above the Fred Hartman Bridge, and the Washburn Tunnel carries traffic under it between Pasadena and Galena Park.
Flat ground and where the water goes
The county falls only a few feet per mile toward the bay, so drainage is slow and rainfall has nowhere to run. Sixteen bayou watersheds cross it — Buffalo, White Oak, Brays, Sims, Greens, Halls, Hunting, Cypress Creek and the San Jacinto River among them — and the Harris County Flood Control District manages them as a single system. Addicks and Barker reservoirs, two dry earthen dams built by the Army Corps of Engineers west of Houston in the 1940s, hold storm runoff off Buffalo Bayou and stay empty most of the year.
Decades of groundwater pumping caused parts of the east and southeast county to sink measurably, which is why the Harris-Galveston Subsidence District now limits well use and the area buys surface water from Lake Houston and Lake Conroe instead. Hurricane Harvey in August 2017 dropped several feet of rain over the county in four days and flooded tens of thousands of buildings, including neighborhoods inside the two reservoir pools. Houston has no zoning ordinance — the only large American city without one — so the pattern of what got built where is set by deed restrictions, drainage rules and the freeways rather than a land-use map.
Landmarks on the map
Texas Medical Center
South of downtown between Loop 610 and SH-288 sits the largest medical complex in the country, a dense block of hospitals, medical schools and research institutions including MD Anderson Cancer Center, Texas Children's Hospital and Houston Methodist. It has its own light-rail stops on the Red Line and employs more people than most Texas counties contain.
Two airports
George Bush Intercontinental (IAH) is 20 miles north of downtown off I-45 and the Hardy Toll Road and handles the long-haul and international traffic. William P. Hobby (HOU), seven miles southeast off I-45 and the Gulf Freeway, is the older field and now the short-haul and low-cost airport. Ellington Field, further south near Clear Lake, serves military, NASA and general aviation.
San Jacinto Battleground
On the marshy point where Buffalo Bayou meets the San Jacinto River at La Porte, Sam Houston's army defeated Santa Anna on 21 April 1836 in a battle that lasted under twenty minutes and ended the Texas Revolution. The San Jacinto Battleground State Historic Site preserves the ground, and the limestone-faced monument raised over it in the 1930s stands above a long reflecting pool with a museum in its base. Battleship Texas was berthed at the site for decades before being towed away for hull repairs.