Lack Township is a township that is located in Juniata County, Pennsylvania, United States. The population was 637 at the time of the 2020 census.

Pennsylvania Route 75 is a 71.2-mile-long (114.6 km) north–south state highway located in central Pennsylvania. The southern terminus is at the Mason–Dixon line in Montgomery Township, where the road continues into Maryland as Maryland Route 494. The northern terminus is at an interchange with U.S. Route 22 and US 322 northeast of Port Royal. PA 75 is a two-lane undivided road that passes through the Ridge-and-Valley Appalachians in Franklin and Juniata counties. The route heads north from the Maryland border in Franklin County to Mercersburg, where it runs concurrent with PA 16 and PA 416. From Mercersburg, PA 75 heads north and crosses US 30 in Fort Loudon before it runs northeast through a long valley, where it has an interchange with the Pennsylvania Turnpike in Willow Hill. The route turns north and heads into Juniata County, where it continues through another valley. PA 75 passes through Port Royal and crosses the Juniata River before it comes to its terminus at US 22/US 322.