Port Royal is a borough in Juniata County, Pennsylvania, United States.

At the time, the Port Royal post office was located in Saint Tammany town, just across the Tuscarora Creek.

However, the Pennsylvania Railroad brought increased traffic through the area and prompted a move of the Port Royal post office into Perrysville in 1847.

The rural counties within Port Royal include Turbett, Spruce Hill and Milford Townships, otherwise known as the Tuscarora Valley.

Port Royal (and Perrysville before it) once was a stop on the old main line of the Pennsylvania Railroad.

From the PRR station during the Gettysburg Campaign of the Civil War, Union scout Stephen W. Pomeroy telegraphed the vital news to Governor Andrew Curtin that Robert E. Lee was concentrating the Army of Northern Virginia at Gettysburg.

This was how state officials learned of this vital intelligence, which Pomeroy had carried for nearly sixty miles from near Lee's headquarters in Chambersburg.

In 1887 the original fairgrounds south of town were found to lack adequate space and a larger tract of land was purchased north of the town, from Smith Kepner, in what is now known as the Juniata County Fair Grounds.