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. In the early part of the 20th century, the main thoroughfare in town was lined with willow trees on both sides for the length of the town, hence the community's name. As time passed and the town grew, the road was widened and sidewalks were installed, which required the trees be removed. Only a few of the original trees remain to this day.

Lancaster County, sometimes nicknamed the Garden Spot of America or Pennsylvania Dutch Country, is a county in the Commonwealth of Pennsylvania. As of the 2020 census, the population was 552,984, making it Pennsylvania's sixth-most populous county. Its county seat is also Lancaster. Lancaster County comprises the Lancaster metropolitan statistical area. The county is part of the South Central region of the state.