Hanover was the site of the final encounter between the Union and Confederate armies before they fought against each other in the Battle of Gettysburg during the American Civil War.

In 1727, John Digges, an Irish nobleman of Prince George's County, Maryland, obtained a grant of 10,000 acres (40 km2) of land where Hanover is now located from Charles Calvert, 5th Baron Baltimore.

The dispute was settled when Maryland and Pennsylvania hired British expert surveyors Charles Mason and Jeremiah Dixon to survey what became known as the Mason–Dixon Line.

McAllister erected a log house at what is now the corner of Baltimore and Middle streets, and opened a store and tavern.

The name Hanover was suggested by Michael Tanner, who was one of the commissioners who laid out York County in 1749 and owned large tracts of land southeast of the town.

[11] Thomas Jefferson spent the night of April 12, 1776 at the Sign of the Horse, an inn, owned by Caspar Reinecker on Frederick Street.

He was on his way from Monticello to Philadelphia to attend the first meeting of the Continental Congress, where on June 10 he would begin to draft the Declaration of Independence.

At the time, Hanover was located at the crossing of two well-traveled roads, one from the port of Baltimore to points north and west and the other between Philadelphia and the Valley of Virginia.

When Jefferson returned from Philadelphia to Monticello, he again dined and spent the night of September 5 at Reinecker's inn.

At the time of the advance of the British on Baltimore in 1814, Hanover and vicinity furnished two companies of infantry commanded by Captain Frederick Metzgar and John Bair.

These two companies left Hanover on foot Sunday morning, August 28, 1814, and reached the city of Baltimore at 9 A.M., Tuesday.

Stuart and a sharp fight ensued in the town and in farm fields to the south, particularly along Frederick Street.

[14] Three days before the battle, another detachment of Virginia cavalry had briefly occupied Hanover, "collecting" supplies and horses from local citizens.

Over the years, its industries have included the making of cigars, gloves, silks, flavine, water wheels, flour, shirts, shoes, machine-shop products, furniture, wire cloth, and ironstone grinders.

The town has lent its name to a brand of canned vegetables, and a mail-order gift company based there.

[15][16] During the summer, White residents were upset by the presence of young Black men in the town square, who had begun to gather there after the local parks were temporarily closed.

In the lead-up to the riot, White residents spat on the Black men visiting their girlfriends in the town square, while the Baltimore Sun reported that there had been tension "building for several weeks," and the Hanover Evening Sun reported that at least one resident "had heard rumors throughout the week that a motorcycle gang was coming into town to start trouble with a few interracial groups of juveniles.

As the smaller side dispersed, police lost control of the rioters, who began to fight using weapons like "baseball bats, knives, tire chains, bricks and hockey sticks," though there was only one serious injury reported.

Nevertheless, many minor skirmishes broke out, and ultimately thirty six people were arrested including the eleven from the day prior.

Hanover Borough council selected Myneca Ojo, 56, to fill the office recently vacated by Ben Adams, who moved away from the community.

The ancestries for Hanover include: German (42%), Irish (11%), United States (10%), English (8%), Italian (3%), and Dutch (2%).

The Vulcan Materials Company owns a large limestone quarry located to the north of Hanover, with an office on Oxford Avenue.