Marklesburg is a borough in Huntingdon County, Pennsylvania, United States.

[4] Marklesburg is located near the western shore of Raystown Lake, just uphill from the flooded village of Aitch.

According to the United States Census Bureau, the borough has a total area of 0.9 square miles (2.3 km2), all land.

There were 138 housing units at an average density of 155.6 per square mile (60.1/km2).

About 3.0% of families and 6.0% of the population were below the poverty line, including none of those under the age of eighteen or sixty five or over.