Willow Street is an unincorporated community and census-designated place (CDP) in Lancaster County, Pennsylvania, United States. The population was 7,578 at the 2010 census. It is primarily in West Lampeter Township, with a portion extending west into Pequea Township. It is bordered to the east by the village of Lampeter.
Pennsylvania Route 272 (Willow Street Pike) is the main highway through the community. It is split into two one-way streets, with the northbound lanes following the original main street through the town, and the southbound lanes running four blocks to the west. PA 272 leads north to the center of Lancaster, the county seat, and south to Wakefield. U.S. Route 222 joins PA 272 in the north part of the CDP (shown as "Mylin Corners" on USGS topographic maps) and leads north into Lancaster but southeast to Quarryville.
According to the United States Census Bureau, the CDP has a total area of , of which , or 0.47%, are water. of 2000, there were 7,258 people, 3,203 households, and 2,091 families living in the CDP. The population density was . There were 3,323 housing units at an average density of . The racial makeup of the CDP was 98.26% White, 0.37% African American, 0.04% Native American, 0.51% Asian, 0.36% from other races, and 0.45% from two or more races. Hispanic or Latino of any race were 1.18% of the population.
There were 3,203 households, out of which 19.2% had children under the age of 18 living with them, 58.7% were married couples living together, 4.9% had a female householder with no husband present, and 34.7% were non-families. Of all households, 32.2% were made up of individuals, and 25.7% had someone living alone who was 65 years of age or older. The average household size was 2.15 and the average family size was 2.69.
In the CDP, the population was spread out, with 17.1% under the age of 18, 4.6% from 18 to 24, 18.9% from 25 to 44, 17.1% from 45 to 64, and 42.4% who were 65 years of age or older. The median age was 54 years. For every 100 females, there were 80.0 males. For every 100 females age 18 and over, there were 76.4 males.
The median income for a household in the CDP was $45,103, and the median income for a family was $58,611. Males had a median income of $43,580 versus $25,523 for females. The per capita income for the CDP was $25,292. About 1.2% of families and 2.8% of the population were below the poverty line, including 2.6% of those under age 18 and 3.8% of those age 65 or over.