Tucson (/ˈtuːsɒn, tuːˈsɒn/) is a city and the county seat of Pima County, Arizona, United States,^[6] and home to the University of Arizona. The 2010 United States Censusput the population at 520,116,^[3] while the 2015 estimated population of the entire Tucson metropolitan statistical area (MSA) was 980,263.^[7] The Tucson MSA forms part of the larger Tucson-Nogales combined statistical area (CSA), with a total population of 1,010,025 as of the 2010 Census. Tucson is the second-largest populated city in Arizona behind Phoenix, both of which anchor the Arizona Sun Corridor. The city is 108 miles (174 km) southeast of Phoenix and 60 mi (97 km) north of the U.S.–Mexico border.^[6] Tucson is the 33rd largest city and the 58th largest metropolitan area in the United States (2014).

Major incorporated suburbs of Tucson include Oro Valley and Marana northwest of the city, Sahuarita^[8] south of the city, and South Tucson in an enclave south of downtown. Communities in the vicinity of Tucson (some within or overlapping the city limits) include Casas Adobes, Catalina Foothills, Flowing Wells, Midvale Park, Tanque Verde, Tortolita, and Vail. Towns outside the Tucson metro area include Benson to the southeast, Catalina and Oracle to the north, and Green Valley to the south.

The Spanish name of the city, Tucsón [tukˈson], is derived from the O’odham Cuk Ṣon [tʃʊk ʂɔːn], meaning “(at the) base of the black [hill]”, a reference to a basalt-covered hill now known as Sentinel Peak, also known as “A” Mountain.^[9] Tucson is sometimes referred to as “The Old Pueblo”.

According to the 2010 American Census Bureau, the racial composition of Tucson was as follows:

• Non-Hispanic White: 47.2%
• Black or African American: 5.0%
• Native American: 2.7%
• Asian: 2.9%
• Native Hawaiian and Other Pacific Islander: 0.2%
• Other race: 17.8%
• Two or more races: 3.4%
• Hispanic or Latino: 41.6%; Mexican Americans made up 36.1% of the city’s population.

As of the census of 2010, there were 520,116 people, 229,762 households, and 112,455 families residing in the city. The population density was 2,500.1 inhabitants per square mile (965.3/km²). There were 209,609 housing units at an average density of 1,076.7 per square mile (415.7/km²). The racial makeup of the city was 69.7% White (down from 94.8% in 1970^[66]), 5.0% Black or African-American, 2.7% Native American, 2.9% Asian, 0.2% Pacific Islander, 16.9% from other races, and 3.8% from two or more races. Hispanic or Latino of any race were 41.6% of the population.^[67] Non-Hispanic Whites were 47.2% of the population in 2010,^[67] down from 72.8% in 1970.^[66]

There were 192,891 households out of which 29.0% had children under the age of 18 living with them, 39.7% were married couples living together, 13.8% had a female householder with no husband present, and 41.7% were non-families. 32.3% of all households were made up of individuals and 9.3% had someone living alone who was 65 years of age or older. The average household size was 2.42 and the average family size was 3.12.

In the inner-city, the population has 24.6% under the age of 18, 13.8% from 18 to 24, 30.5% from 25 to 44, 19.2% from 45 to 64, and 11.9% who were 65 years of age or older. The median age was 32 years. For every 100 females, there were 96.0 males. For every 100 females age 18 and over, there were 93.3 males.

The median income for a household in the city was $30,981, and the median income for a family was $37,344. Males had a median income of $28,548 versus $23,086 for females. The per capita income for the city was $16,322. About 13.7% of families and 18.4% of the population were below the poverty line, including 23.6% of those under age 18 and 11.0% of those age 65 or over.^[68]