Kirkwood is an unincorporated farming town and census-designated place in Colerain Township, Lancaster County, Pennsylvania, United States. It is part of the Lancaster Metro area, in Pennsylva…Kirkwood is an unincorporated farming town and census-designated place in Colerain Township, Lancaster County, Pennsylvania, United States. It is part of the Lancaster Metro area, in Pennsylvania Dutch Country. The ZIP code is 17536. As of the 2010 census the population was 396.