Williamsport is the larger principal city of the Williamsport-Lock Haven CSA, a Combined Statistical Area that includes the Williamsport metropolitan area (Lycoming County) and the Lock Haven micropolitan area (Clinton County), which had a combined population of 157,958 at the 2000 census.
As of the census of 2000, there were 30,706 people, 12,219 households, and 6,732 families residing in the city. The population density was 3,456.3 people per square mile (1,335.1/km²). There were 13,524 housing units at an average density of 1,522.3/sq mi (588.0/km²). The racial makeup of the city was 84.11% White, 12.73% African American, 0.36% Native American, 0.57% Asian, 0.01% Pacific Islander, 0.48% from other races, and 1.73% from two or more races. Hispanic or Latino of any race were 1.11% of the population.
There were 12,219 households out of which 27.4% had children under the age of 18 living with them, 34.9% were married couples living together, 15.5% had a female householder with no husband present, and 44.9% were non-families. 35.1% of all households were made up of individuals and 12.9% had someone living alone who was 65 years of age or older. The average household size was 2.30 and the average family size was 2.97.
In the city the population was spread out with 22.5% under the age of 18, 18.0% from 18 to 24, 26.7% from 25 to 44, 19.4% from 45 to 64, and 13.5% who were 65 years of age or older. The median age was 32 years. For every 100 females there were 97.7 males. For every 100 females age 18 and over, there were 95.9 males.
The median income for a household in the city was $25,946, and the median income for a family was $33,844. Males had a median income of $26,668 versus $20,196 for females. The per capita income for the city was $14,707. About 13.7% of families and 21.5% of the population were below the poverty line, including 24.0% of those under age 18 and 11.6% of those age 65 or over.
Williamsport operates on a "Strong Mayor" form of governing, meaning the mayor is given almost total administrative authority and a clear, wide range of political independence with the power to appoint and dismiss department heads without council approval and little public input. The current mayor of the City of Williamsport is Dr. Gabriel J. Campana.
See also: List of Mayors of Williamsport, Pennsylvania
Williamsport Regional Airport (IPT), located several miles east of the city in the borough of Montoursville, has three flights daily via US Airways (as of January 2009). Susquehanna Trailways provides daily long distance bus service from a station in the downtown to Elmira, New York, Harrisburg, New York City, and Philadelphia. Local bus service within Williamsport and to other places in Lycoming County near the river is offered by River Valley Transit.
Williamsport is served by several major highways, including Interstate 180, U.S. Route 15, and U.S. Route 220. I-180 and US 220 currently run together northeast/southwest through Williamsport, and US 15 joins (in the opposite direction) for two miles. Once completed, Interstate 99 will enter Williamsport from the southwest on US 220 and continue north on US 15, joining only one at a time. Train freight service (west to Avis and east to Muncy) is provided by the Lycoming Valley Railroad, which has its main yard in the Newberry section of Williamsport, and offers connections to the Norfolk Southern and Canadian Pacific railroads. The West Branch Susquehanna River is not navigable, but a dam at Hepburn Street provides a large lake for recreational boating, including outings on the mock paddlewheeler Hiawatha from Susquehanna State Park.