Twin Falls is the largest city of Idaho's Magic Valley region and the seventh largest in the state. As the largest city in a 100-mile (166-kilometer) radius, Twin Falls serves as a regional commercial center for both south-central Idaho and northeastern Nevada.
Twin Falls is the principal city of the Twin Falls, ID Micropolitan Statistical Area - the state's largest - which officially includes Jerome and Twin Falls Counties. The resort community of Jackpot, Nevada, in Elko County is unofficially considered part of the greater Twin Falls area.
As of the census of 2000, there were 34,469 people, 13,274 households, and 8,867 families residing in the city. The population density was 2,870.1 people per square mile (1,108.1/km²). There were 14,162 housing units at an average density of 1,179.2/sq mi (455.3/km²). The racial makeup of the city was 91.77% White, 0.22% African American, 0.74% Native American, 1.09% Asian, 0.11% Pacific Islander, 3.71% from other races, and 2.35% from two or more races. Hispanic or Latino of any race were 8.89% of the population.
There were 13,274 households out of which 32.9% had children under the age of 18 living with them, 51.7% were married couples living together, 11.0% had a female householder with no husband present, and 33.2% were non-families. 26.8% of all households were made up of individuals and 10.7% had someone living alone who was 65 years of age or older. The average household size was 2.51 and the average family size was 3.05.
In the city the population was spread out with 26.5% under the age of 18, 12.1% from 18 to 24, 26.2% from 25 to 44, 20.2% from 45 to 64, and 15.0% who were 65 years of age or older. The median age was 34 years. For every 100 females there were 92.5 males. For every 100 females age 18 and over, there were 89.5 males.
The median income for a household in the city was $42,641, and the median income for a family was $48,632. Males had a median income of $34,742 versus $20,934 for females. The per capita income for the city was $16,439. About 9.8% of families and 14.1% of the population were below the poverty line, including 17.5% of those under age 18 and 9.3% of those age 65 or over.
Although Twin Falls has the distinction of being the largest Idaho city not directly on the Interstate Highway System, the city is served by several major highways including U.S. Route 30 and U.S. Route 93. Access to Interstate 84 is afforded by a junction with U.S. Route 93 approximately 5 miles (8.3 km) north of the city in Jerome County. Idaho State Highway 74 provides direct access from downtown Twin Falls to southbound locations on U.S. Route 93, including Hollister, Rogerson, and Jackpot, Nevada.
Trans IV, a small public transportation system operated by the College of Southern Idaho, is also available.
Limited commercial air service is provided at Joslin Field-Magic Valley Regional Airport. As of August 2008 daily flights to Salt Lake City International Airport are operated by SkyWest Airlines using the Embraer EMB 120 Brasilia.