Mount Union borough

Mount Union's Powder Plant

Shirley Street at Jefferson Street, downtown Mount Union, February 1990Jet Lowe, Historic American Engineering Record, 1990. Public domain, via Wikimedia Commons. Public domain

Did you know? Mount Union was a First World War boomtown. In 1915 the Aetna Explosives Company opened a powder plant just across the river from the town. In July 1915 the Harrisburg Telegraph reported that the new plant, then being rushed to completion, was to make powder and shells for the Allies. On August 7 the paper said the company expected to be making powder there by August 15, with more than 1,000 men employed.

A 1991 National Park Service survey says the plant stood in the river loop area east of Mount Union. The sources differ on whom it served. The survey says that before the United States entered the war, the factory produced gunpowder "for the use of various European armies in the fight against Germany." The National Register nomination for the town's historic district calls the plant federally sponsored. And on July 29, 1916, the Telegraph reported that the company had received an order for 5,000,000 pounds of smokeless powder for the United States government, to be filled at Mount Union.

The Harrisburg Telegraph of October 2, 1916, reported that the company had about stopped making powder and that about one hundred men remained at the plant. The shutdown was said to be for repairs and the installation of safety devices, and the men let go were told they would be sent for when operations started again in several months on a larger scale. The item ran twelve days after a September explosion at the plant had killed six men. On November 21 the Telegraph reported the superintendent's announcement that the plant, closed since October, would soon be running again, with at least 1,500 men employed within several weeks.

The plant ran twenty four hour shifts until it closed at the end of 1918, after the armistice. The Harrisburg Telegraph of Thursday, January 2, 1919, reported that the plant had shut down on Tuesday evening and that 500 employees were thrown out of work. The National Park Service survey gives an earlier date, saying the plant officially closed its doors on November 11, 1918, with the end of the First World War. The Telegraph's Mount Union news of December 3, 1918, reported that the plant had been reorganized over the previous ten days, with the hours changed, new work cut back and surplus help eliminated, and that several hundred men had left town in the past week. The item said the closing of these plants, the Aetna works and a new government sulfuric acid plant nearby, would work no hardship on the town, since there was plenty of work for all. The Historic American Buildings Survey says it employed at least 1,000 men and women, and that the brickyards and the powder plant together employed around 3,000. The National Register nomination for the town's historic district says the plant employed hundreds of workers in round the clock shifts.

After the plant closed, it was offered for sale. The Lake County Times of Hammond, Indiana, reported on September 5, 1919, that the Aetna plants, the one at Mount Union among them, had been advertised for sale. In June 1921 newspapers reported that Hercules Powder had taken over the properties, assets and business of the Aetna Explosives Company. The National Park Service survey says the Mount Union land was sold to Hercules Powder, but the list of plants printed in the Evening Journal of Wilmington, Delaware, does not include Mount Union. The survey says Hercules then sold the land and buildings, and that a few storage buildings, an uncompleted ordnance building and several company houses still remained at the site near Silverford Heights in 1991.

The Historic American Buildings Survey says the munitions jobs paid well but were dangerous and short term. They drew mostly single men from a wide radius around Mount Union, and the company built a few single family houses for its managers and several two and three story barracks style buildings for the rest of its employees.

Before the war, the nomination says, Mount Union's population had been relatively homogeneous. The influx of thousands of new workers drawn and recruited to the Aetna plant changed the ethnic and racial face of the town, bringing eastern and southern Europeans and African Americans.

Within a decade, the nomination says, certain areas of the town had earned a regional reputation for "racketeering," as the local writer James T. McElroy described things in 1930. The Historic American Buildings Survey calls it a local reputation and gives the phrase as "a racketeering borough ... a second Sodom and Gomorrah."

Checked against the record. Confirmed 2026-10-30 against the sources listed: the factual sentences were matched to passages in their sources. Where sources disagreed on a number, the number was left out. Rechecked 1 November 2026. The page spelled the company Etna, as the 1994 district nomination and some 1915 papers do; the Harrisburg Telegraph of July 1915, 1916 and 1919 names it the Aetna Explosives Company, and the page now does. The closing is now given both ways: the Harrisburg Telegraph of 2 January 1919 says the plant had shut down on Tuesday evening, and a 1991 National Park Service survey says it closed on November 11, 1918. The 1916 shutdown and reopening, and the December 1918 layoffs, come from the Harrisburg Telegraph. We found no closing order from November 1918 in the Telegraph issues we searched. A Telegraph item of January 17, 1919, offers for sale a large Aetna plant near Newton Hamilton. It may be this plant, but we could not confirm that, so it is not used. The sale of the Mount Union land to Hercules Powder rests on the 1991 survey alone, and no deed has been seen. Whom the plant served is given in each source's own terms, because they differ: the Telegraph of 14 July 1915 says the Allies, the 1991 survey says European armies before the United States entered the war, the National Register nomination says federally sponsored, and the Telegraph of 29 July 1916 reports a United States government order. None names a particular foreign buyer. We have not seen a contract or shipping record, so how much powder went overseas, and whether the 1916 order was filled, stay open.

Sources