Middleburg is a borough in Snyder County, Pennsylvania, United States. The population was 1,382 at the 2000 census. It is the county seat of Snyder County.
Native Americans had lived in the region for centuries. White settlers are recorded living in the area in 1755. Middleburg was originally named Swinefordstown (Swinefordstettle in the Pennsylvania Dutch dialect) after John Albright Swineford who ran a tavern here in 1787. He was also the owner of land located on the north bank of the Middle Creek on which engineer Frederick Evans laid out the town in 1800. This town became known as Middleburgh circa 1825, and was incorporated as a borough in 1864.
A portion of the site that Middleburg occupies was the location of the Stump's Run Massacre in January of 1768. Stump's Run is located to the west of the Glendale Cemetery and is also near the Snyder County Historical Society. In this incident, two colonists named Frederick Stump and John Ironcutter were found to be responsible for the deaths of four Native American men, three Native American women, and three children over a two day period. Four of the men and two of the women were killed at Stump's cabin, which was located at the mouth of the Middle Creek near Selinsgrove. After Stump and Ironcutter shoved the bodies through a hole in the ice, they traveled up the creek to Stump's Run to kill the remaining woman and the children. These bodies were thrown into the native cabins, and the cabins burned. Although the men claimed self-defense, it is suspected that this could have been provoked by a drunken brawl, or that the natives were killed by Stump in retaliation for the deaths of his wife and children at the hands of Native American raiders. The two men were arrested and taken to the Cumberland County jail at Carlisle for trial, but were freed at the hands of a sympathetic mob. The men were never recaptured.