The Houston area is located on land that was once home of the Karankawa (kə rang′kə wä′,-wô′,-wə) and the Atakapa (əˈtɑːkəpə) indigenous peoples for at least 2,000 years before the first known settlers arrived. These tribes are almost nonexistent today; this was most likely caused by foreign disease, and competition with various settler groups in the 18th and 19th centuries. However, the land remained largely uninhabited until settlement in the 1830s.

The Allen brothers—Augustus Chapman and John Kirby—explored town sites on Buffalo Bayou and Galveston Bay. According to historian David McComb, "[T]he brothers, on August 26, 1836, bought from Elizabeth E. Parrott, wife of T.F.L. Parrott and widow of John Austin, the south half of the lower league [2,214-acre (896 ha) tract] granted to her by her late husband. They paid $5,000 total, but only $1,000 of this in cash; notes made up the remainder."

The Allen brothers ran their first advertisement for Houston just four days later in the Telegraph and Texas Register, naming the notional town in honor of President Sam Houston. They successfully lobbied the Republic of Texas Congress to designate Houston as the temporary capital, agreeing to provide the new government with a state capitol building. About a dozen persons resided in the town at the beginning of 1837, but that number grew to about 1,500 by the time the Texas Congress convened in Houston for the first time that May. The Republic of Texas granted Houston incorporation on June 5, 1837, as James S. Holman became its first mayor. In the same year, Houston became the county seat of Harrisburg County (now Harris County).

In 1839, the Republic of Texas relocated its capital to Austin. The town suffered another setback that year when a yellow fever epidemic claimed about one life for every eight residents, yet it persisted as a commercial center, forming a symbiosis with its Gulf Coast port, Galveston. Landlocked farmers brought their produce to Houston, using Buffalo Bayou to gain access to Galveston and the Gulf of Mexico. Houston merchants profited from selling staples to farmers and shipping the farmers' produce to Galveston.

The great majority of enslaved people in Texas came with their owners from the older slave states. Sizable numbers, however, came through the domestic slave trade. New Orleans was the center of this trade in the Deep South, but slave dealers were in Houston. Thousands of enslaved black people lived near the city before the American Civil War. Many of them near the city worked on sugar and cotton plantations, while most of those in the city limits had domestic and artisan jobs.^{[citation needed]}

In 1840, the community established a chamber of commerce, in part to promote shipping and navigation at the newly created port on Buffalo Bayou.

By 1860, Houston had emerged as a commercial and railroad hub for the export of cotton. Railroad spurs from the Texas inland converged in Houston, where they met rail lines to the ports of Galveston and Beaumont. During the American Civil War, Houston served as a headquarters for General John Magruder, who used the city as an organization point for the Battle of Galveston. After the Civil War, Houston businessmen initiated efforts to widen the city's extensive system of bayous so the city could accept more commerce between Downtown and the nearby port of Galveston. By 1890, Houston was the railroad center of Texas.^{[citation needed]}

In 1900, after Galveston was struck by a devastating hurricane, efforts to make Houston into a viable deep-water port were accelerated. The following year, the discovery of oil at the Spindletop oil field near Beaumont prompted the development of the Texas petroleum industry. In 1902, President Theodore Roosevelt approved a $1 million improvement project for the Houston Ship Channel. By 1910, the city's population had reached 78,800, almost doubling from a decade before. African Americans formed a large part of the city's population, numbering 23,929 people, which was nearly one-third of Houston's residents.

President Woodrow Wilson opened the deep-water Port of Houston in 1914, seven years after digging began. By 1930, Houston had become Texas's most populous city and Harris County the most populous county. In 1940, the U.S. Census Bureau reported Houston's population as 77.5% White and 22.4% Black.

When World War II started, tonnage levels at the port decreased and shipping activities were suspended; however, the war did provide economic benefits for the city. Petrochemical refineries and manufacturing plants were constructed along the ship channel because of the demand for petroleum and synthetic rubber products by the defense industry during the war.Ellington Field, initially built during World War I, was revitalized as an advanced training center for bombardiers and navigators. The Brown Shipbuilding Company was founded in 1942 to build ships for the U.S. Navy during World War II. Due to the boom in defense jobs, thousands of new workers migrated to the city, both blacks and whites competing for the higher-paying jobs. President Roosevelt had established a policy of nondiscrimination for defense contractors, and blacks gained some opportunities, especially in shipbuilding, although not without resistance from whites and increasing social tensions that erupted into occasional violence. Economic gains of blacks who entered defense industries continued in the postwar years.

In 1945, the M.D. Anderson Foundation formed the Texas Medical Center. After the war, Houston's economy reverted to being primarily port-driven. In 1948, the city annexed several unincorporated areas, more than doubling its size. Houston proper began to spread across the region. In 1950, the availability of air conditioning provided impetus for many companies to relocate to Houston, where wages were lower than those in the North; this resulted in an economic boom and produced a key shift in the city's economy toward the energy sector.

The increased production of the expanded shipbuilding industry during World War II spurred Houston's growth, as did the establishment in 1961 of NASA's "Manned Spacecraft Center" (renamed the Lyndon B. Johnson Space Center in 1973). This was the stimulus for the development of the city's aerospace industry. The Astrodome, nicknamed the "Eighth Wonder of the World", opened in 1965 as the world's first indoor domed sports stadium.

During the late 1970s, Houston had a population boom as people from the Rust Belt states moved to Texas in large numbers. The new residents came for numerous employment opportunities in the petroleum industry, created as a result of the Arab oil embargo. With the increase in professional jobs, Houston has become a destination for many college-educated persons, most recently including African Americans in a reverse Great Migration from northern areas.

In 1997, Houstonians elected Lee P. Brown as the city's first African American mayor.

In June 2001, Tropical Storm Allison dumped up to 40 inches (1,000 mm) of rain on parts of Houston, causing what was then the worst flooding in the city's history. The storm cost billions of dollars in damage and killed 20 people in Texas. By December of the same year, Houston-based energy company Enron collapsed into the largest U.S. bankruptcy (at that time), a result of being investigated for off-the-books partnerships that were allegedly used to hide debt and inflate profits. The company lost no less than $70 billion.

In August 2005, Houston became a shelter to more than 150,000 people from New Orleans, who evacuated from Hurricane Katrina. One month later, about 2.5 million Houston-area residents evacuated when Hurricane Rita approached the Gulf Coast, leaving little damage to the Houston area. This was the largest urban evacuation in the history of the United States. In September 2008, Houston was hit by Hurricane Ike. As many as 40% of residents refused to leave Galveston Island because they feared the type of traffic problems that had happened after Hurricane Rita.

During its recent history, Houston has flooded several times from heavy rainfall, which has been becoming increasingly common. This has been exacerbated by a lack of zoning laws, which allowed unregulated building of residential homes and other structures in flood-prone areas. During the floods in 2015 and 2016, each of which dropped at least a foot of rain, parts of the city were covered in several inches of water. Even worse flooding happened in late August 2017, when Hurricane Harvey stalled over southeastern Texas, much like Tropical Storm Allison did sixteen years earlier, causing severe flooding in the Houston area, with some areas receiving over 50 inches (1,300 mm) of rain. The rainfall exceeded 50 inches in several areas locally, breaking the national record for rainfall. The damage for the Houston area is estimated at up to $125 billion U.S. dollars, and it is considered to be one of the worst natural disasters in the history of the United States, with the death toll exceeding 70 people. On January 31, 2018, the Houston City Council agreed to forgive large water bills thousands of households faced in the aftermath of Hurricane Harvey, as Houston Public Works found 6,362 homeowners' water utility bills had at least doubled.

Houston has also been the site of numerous industrial disasters and construction accidents. In 2019, OSHA found that Texas was the leading state in the nation for crane accidents. In Houston, a 2008 crane collapse at a refinery killed four people and injured six. The crane that collapsed was one of the largest cranes in the nation, possessing a 400-foot boom that could lift more than a million pounds. Due to the industrial infrastructure in and around Houston, natural disasters such as Hurricane Harvey have also led to numerous toxic spills and disasters, including the 2017 Arkema plant explosion.

The 2010 United States Census reported that Houston had a population of 2,100,263 residents. In 2017, the census-estimated population rose to 2,312,717, and in 2018 to 2,325,502. An estimated 600,000 illegal immigrants resided in the Houston area in 2017, comprising nearly 9% of the city's metropolitan population. The 2019 census estimates determined a population of 2,320,268 and the American Community Survey 2,316,797, citing a slight decline due to suburbanization.

Per the American Community Survey's 2014-2018 estimates, Houston's age distribution was 486,083 under 15; 147,710 aged 15 to 19; 603,586 aged 20 to 34; 726,877 aged 35 to 59; and 357,834 aged 60 and older. The median age was 33.1, up from 32.9 in 2017 and down from 33.5 in 2014; the city's youthfulness was attributed to an influx of an African American New Great Migration, Hispanic or Latin American, and Asian immigrants into Texas. For every 100 females, there were 98.5 males.

There were 976,745 housing units in 2018 and 849,105 households. An estimated 42.9% of Houstonians owned housing units with an average of 2.67 persons per household. The median monthly owner costs with a mortgage were $1,598, and $524 without a mortgage. Houston's median gross rent from 2014 to 2018 was $990. The median household income in 2018 was $51,140 and 20.6% of Houstonians lived at or below the poverty line.

Houston is a majority-minority city. The Rice University Kinder Institute for Urban Research, a think tank, has described Greater Houston as "one of the most ethnically and culturally diverse metropolitan areas in the country". Houston's diversity, historically fueled by large waves of Hispanic or Latino and Asian immigrants, has been attributed to its relatively low cost of living, strong job market, and role as a hub for refugee resettlement. Houston has long been known as a popular destination for African Americans due to the city's well-established and influential Black or African American community. The Houston area is also home to the largest African American community in Texas. A 2012 Kinder Institute report found that, based on the evenness of population distribution between the four major racial groups in the United States (non-Hispanic white, non-Hispanic black, Hispanic or Latino, and Asian), Greater Houston was the most ethnically diverse metropolitan area in the United States, ahead of New York City.

In 2017, according to the U.S. Census Bureau, non-Hispanic whites made up 24.9% of the population of Houston proper, Hispanics or Latinos 44.5%, Blacks or African Americans 29.9%, and Asian Americans 6.7%. In 2018, non-Hispanic whites made up 20.7% of the population, Hispanics or Latinos 44.9%, Blacks or African Americans 30.3%, and Asian Americans 8.2%. The largest Hispanic or Latin American ethnic groups in the city were Mexican Americans (31.6%), Puerto Ricans (0.8%), and Cuban Americans (0.8%) in 2018.

Houston has a higher proportion of minorities than non-Hispanic whites. In 2010, whites (including Hispanic whites) made up 57.6% of the city of Houston's population; 24.6% of the total population was non-Hispanic whites. Blacks or African Americans made up 22.5% of Houston's population, American Indians made up 0.3% of the population, Asians made up 6.9% (1.7% Vietnamese, 1.3% Chinese, 1.3% Indian, 0.9% Pakistani, 0.4% Filipino, 0.3% Korean, 0.1% Japanese) and Pacific Islanders made up 0.1%. Individuals from some other race made up 15.69% of the city's population. Individuals from two or more races made up 2.1% of the city.

At the 2000 U.S. census, the racial makeup of the city in was 49.3% White, 25.3% Black or African American, 5.3% Asian, 0.7% American Indian, 0.1% Pacific Islander, 16.5% from some other race, and 3.1% from two or more races. In addition, Hispanics made up 37.4% of Houston's population in 2000, while non-Hispanic whites made up 30.8%. The proportion of non-Hispanic whites in Houston has decreased significantly since 1970, when it was 62.4%.

Houston is home to one of the largest LGBT communities and pride parades in the United States. In 2018 the city scored a 70 out of 100 for LGBT friendliness. Jordan Blum of the Houston Chronicle stated levels of LGBT acceptance and discrimination varied in 2016 due to some of the region's traditionally conservative culture.

Before the 1970s, the city's gay bars were spread around Downtown Houston and what is now midtown Houston. LGBT Houstonians needed to have a place to socialize after the closing of the gay bars. They began going to Art Wren, a 24-hour restaurant in Montrose. LGBT community members were attracted to Montrose as a neighborhood after encountering it while patronizing Art Wren, and they began to gentrify the neighborhood and assist its native inhabitants with property maintenance. Within Montrose, new gay bars began to open. By 1985, the flavor and politics of the neighborhood were heavily influenced by the LGBT community, and in 1990, according to Hill, 19% of Montrose residents identified as LGBT. Paul Broussard was murdered in Montrose in 1991.

In February 2015, a 17-year-old gay student at Lutheran High School North reported that the school forced him to leave since he refused to take down YouTube videos discussing his sexuality. The school's executive director, Wayne Kramer, referred to the student handbook, which stated: "Lutheran High North reserves the right, within its sole discretion, to refuse admission of an applicant and/or to discontinue enrollment of a current student participating in, promoting, supporting or condoning: pornography, sexual immorality, homosexual activity or bisexual activity".

Before the legalization of same-sex marriage in the United States the first marriage in Houston took place on October 5, 1972. Houston elected the first openly lesbian mayor of a major city in 2009, and she served until 2016. During her tenure she authorized the Houston Equal Rights Ordinance which was intended to improve anti-discrimination coverage based on sexual orientation and gender identity in the city, specifically in areas such as housing and occupation where no anti-discrimination policy existed.

Houston and its metropolitan area are the third-most religious and Christian area by percentage of population in the United States, and second in Texas behind the Dallas–Fort Worth metroplex. Historically, Houston has been a center of Protestant Christianity, being part of the Bible Belt. Other Christian groups including Eastern and Oriental Orthodox Christianity, and non-Christian religions did not grow for much of the city's history because immigration was predominantly from Western Europe (which at the time was dominated by Western Christianity and favored by the quotas in federal immigration law). The Immigration and Nationality Act of 1965 removed the quotas, allowing for the growth of other religions.

According to a 2014 study by the Pew Research Center, 73% of the population of the Houston area identified themselves as Christians, about 50% of whom claimed Protestant affiliations and about 19% claimed Roman Catholic affiliations. Nationwide, about 71% of respondents identified as Christians. About 20% of Houston-area residents claimed no religious affiliation, compared to about 23% nationwide. The same study says that area residents identifying with other religions (including Judaism, Buddhism, Islam, and Hinduism) collectively made up about 7% of the area population.

Lakewood Church in Houston, led by Pastor Joel Osteen, is the largest church in the United States. A megachurch, it had 44,800 weekly attendees in 2010, up from 11,000 weekly in 2000. Since 2005, it has occupied the former Compaq Center sports stadium. In September 2010, Outreach Magazine published a list of the 100 largest Christian churches in the United States, and on the list were the following Houston-area churches: Lakewood, Second Baptist Church Houston, Woodlands Church, Church Without Walls, and First Baptist Church. According to the list, Houston and Dallas were tied as the second-most popular city for megachurches.

The Roman Catholic Archdiocese of Galveston-Houston, the largest Catholic jurisdiction in Texas and fifth-largest in the United States, was established in 1847. The Roman Catholic Archdiocese of Galveston-Houston claims approximately 1.7 million Catholics within its boundaries. Other prominent Catholic jurisdictions include the Eastern Catholic Ruthenian Greek Catholic Church and Ukrainian Greek Catholic Church.

A variety of Eastern and Oriental Orthodox churches can be found in Houston. Immigrants from Eastern Europe, the Middle East, Ethiopia, India, and other areas have added to Houston's Eastern and Oriental Orthodox population. As of 2011 in the entire state, 32,000 people actively attended Orthodox churches. In 2013 Father John Whiteford, the pastor of St. Jonah Orthodox Church near Spring, stated that there were about 6,000-9,000 Eastern Orthodox Christians in Houston. The most prominent Eastern and Oriental Orthodox jurisdictions are the Greek Orthodox Archdiocese of America, the Antiochian Orthodox Archdiocese of North America, the Coptic Orthodox Church of Alexandria, and Ethiopian Orthodox Tewahedo Church.

Houston's Jewish community, estimated at 47,000 in 2001, has been present in the city since the 1800s. Houstonian Jews have origins from throughout the United States, Israel, Mexico, Russia, and other places. As of 2016, over 40 synagogues were in Greater Houston. The largest synagogues are Congregation Beth Yeshurun, a Conservative Jewish temple, and the Reform Jewish congregations Beth Israel and Emanu-El. According to a study in 2016 by Berman Jewish DataBank, 51,000 Jews lived in the area, an increase of 4,000 since 2001.

Houston has a large and diverse Muslim community; it is the largest in Texas and the Southern United States, as of 2012. It is estimated that Muslims made up 1.2% of Houston's population. As of 2016, Muslims in the Houston area included South Asians, Middle Easterners, Africans, Turks, and Indonesians. In 2000 there were over 41 mosques and storefront religious centers, with the largest being the Al-Noor Mosque (Mosque of Light) of the Islamic Society of Greater Houston. The Hindu, Sikh, and Buddhist communities form a growing sector of the religious demographic after Judaism and Islam. One of the largest Hindu temples in the metropolitan area is BAPS Shri Swaminarayan Mandir Houston, affiliated with the Swaminarayan Sampradaya denomination. Of the irreligious community 16% practiced nothing in particular, 3% were agnostic, and 2% were atheist.