In the mid- to late 20th century, the city's economic fortunes fluctuated with its major industries consisting of government, heavy manufacturing, agriculture, and food services.

[14] During the first part of the 19th century, Harrisburg was a notable stopping place along the Underground Railroad, as persons escaping slavery used the Susquehanna River to access food and supplies before heading north towards Canada.

[15] During the American Civil War, Harrisburg was a significant training center for the Union Army, with tens of thousands of troops passing through Camp Curtin.

It was also a major rail center for the Union and a vital link between the Atlantic coast and the Midwest, with several railroads running through the city and spanning the Susquehanna River.

Under orders from Gen. Robert E. Lee directly, Confederate Lt. Gen. Richard S. Ewell's Second Corps were tasked with capturing Harrisburg and disrupting the vital Union supply and rail lines.

The city was the center of enormous railroad traffic and its steel industry supported large furnaces, rolling mills, and machine shops.

It was a wide swath of flat land located south of the city, with rail and canal access running its entire 4 mile length.

[18] Allison Hill, Harrisburg's first suburb, is located east of the city on a prominent bluff, accessed by bridges across a wide swath of train tracks.

It was developed in the late 19th century and offered affluent Harrisburg residents the opportunity to live in the suburbs only a few hundred yards from their jobs in the city.

[19] In December 1900, a reformer named Mira Lloyd Dock, who had recently encountered well-ordered urban centers on an international trip to Europe, gave a lecture on "The City Beautiful" to Harrisburg's Board of Trade.

In addition, schemes were undertaken for new water filtration, burial of electric wires, the paving of roads, and the creation of a modern sanitary sewer system.

The efforts to improve the city also paralleled the construction of an expanded monumental Capitol complex in 1906 which led, in turn, to the displacement of the Old Eighth Ward, one of the most ethnically and racially diverse communities in Harrisburg.

After being held in place for about 5 years by WWII armament production, the population peaked shortly after the war, but then took a long-overdue dive as people fled from the city.

On March 28, 1979, the Three Mile Island nuclear plant, along the Susquehanna River located in Londonderry Township which is south of Harrisburg, suffered a partial meltdown.

Governor Dick Thornburgh, on the advice of Nuclear Regulatory Commission Chairman Joseph Hendrie, advised the evacuation "of pregnant women and pre-school age children ... within a five-mile radius of the Three Mile Island facility."

For example, during a budget crisis the city was forced to sell $8 million worth of Western and American-Indian artifacts collected by Mayor Reed for a never-realized museum celebrating the American West.

[24] Infrastructure was left unrepaired, and the heart of the city's financial woes was a trash-to-electricity plant, the Harrisburg incinerator, which was supposed to generate income but instead, because of increased borrowing, incurred a debt of $320 million.

[35] Unkovic blamed disdain for legal restraints on contracts and debt for creating Harrisburg's intractable financial problem and said the corrupt influence of creditors and political cronies prevented fixing it.

[42][43] Receiver Lynch had also called for setting up nonprofit investment corporations to oversee infrastructure improvement, repairing the city's crumbling roads and water and sewer lines, and pensions and economic development.

[70] With the increase of the city's prominence as an industrial and transportation center, Harrisburg reached its peak population build up in 1950, topping out at nearly 90,000 residents.

Fiberglass sculptures of cows are decorated by local artists, and distributed over the city center, in public places such as train stations and parks.

With gradual but steady increases in the number and variety of multi-purpose venues, bars, and restaurants since the mid-2010s, as well as large concerts sponsored by Harrisburg University, the live music and entertainment scene expanded to a "mini-explosion" by 2022 of big artists with a wide draw from both near and far.

The Senators played a few more seasons before flood waters destroyed Island Field in 1936, effectively ending Eastern League participation for fifty-one years.

The passenger rail operator runs its Keystone Service and Pennsylvanian routes between New York, Philadelphia, and the Harrisburg Transportation Center daily.

It also eliminated the need to change locomotives at 30th Street Station from diesel to electric and vice versa for trains continuing to or coming from New York City.

[105][106] Harrisburg is served by several major highways, including Interstate 76 (I-76, Pennsylvania Turnpike), which passes south of the city and accesses two interchanges, running west to Pittsburgh and east to Philadelphia.

U.S. Route 11 (US 11) and US 15 pass through the western suburbs of Harrisburg, heading north concurrently from Camp Hill up the west bank of the Susquehanna River toward Selinsgrove.

Walnut Street Bridge, now used only by pedestrians and cyclists, links the downtown and Riverfront Park areas with City Island but goes no further as spans are missing on its western side due to massive flooding resulting from the North American blizzard of 1996.

Because it is the seat of government for the state and lies relatively close to other urban centers, Harrisburg has played a significant role in the nation's political, cultural and industrial history.

Secretaries of War, Simon Cameron and Alexander Ramsey and several other prominent political figures, such as former speaker of the house Newt Gingrich, hail from Harrisburg.