Pennsylvania agriculture has been in a continuous state of change since the founding of the colony. The changes have been gradual and evolutionary, but three distinct periods are recognizable. The pioneer era, during which the land was cleared, lasted from 1682 to the 1830s. Subsistence farming predominated during that time, in which the farm provided food for the family and a small surplus that could be sold to the local community. The second period (c. 1830 to the 1920s) was dominated by general agriculture, in which farmers produced food to supply an expanding urban economy. Most agricultural machinery was invented during that period, which made it possible to farm more land and increase production of all kinds of products. However, by the 1920s the cost of agricultural production in Pennsylvania was higher than in any other state in the country, and Pennsylvania agriculture entered a third stage, in which farmers began to focus on more specialized products. Over time, most of the poor farmland was abandoned.

Pennsylvania has one of the largest rural populations in the United States, and nearly one-third of the state is still under cultivation. Livestock—including dairy and beef cattle, hogs, and sheep—and livestock products are the major components of farm income. Pennsylvania is a major producer of milk, eggs, and poultry; fruits, including peaches, grapes, cherries, and apples; hay; corn (maize); mushrooms; and Christmas trees. Ice cream and sausages are important processed food products.

Resources and power

Hydrocarbons—bituminous (soft) coal, anthracite (hard coal), petroleum, and natural gas—provide a vast majority of the mineral wealth of the state. Pennsylvania has also been a major producer of such nonmetallic minerals as limestone, slate, sand, and gravel. Small iron ore deposits provided the basis of early iron furnaces, but the major deposits of iron ore that were located in Cornwall and Morgantown have since been abandoned.

Bituminous coal beds are located in portions of 33 Pennsylvania counties and constitute more than one-fourth of the state’s total area. Maximum production was reached in 1918, when nearly 200 million tons of coal were mined. Since the late 20th century, production has fallen to roughly one-fourth of that annually, owing to competition from petroleum and natural gas as well as the existence now of environmental laws that limit the consumption of sulfur-containing coal. Pennsylvania has the only significant deposits of anthracite in the country. Production peaked in 1917, when more than 100 million tons were mined; however, production has also declined—even more precipitously than it has for bituminous—because of competition from other available energy sources.

Northwestern Pennsylvania was the site of the world’s first successful oil well (1859, near Titusville) and its first oil boom, in the 1860s. The state’s oil fields are now nearly exhausted, but natural gas production remains significant, and Pennsylvania still has one of the largest oil-refining capacities of any state on the East Coast.

Britannica Quiz

U.S. State Capitals Quiz

Although coal production is only a fraction of previous levels, coal-fired thermal plants still generate most of the state’s electric power, with natural gas and oil also used in considerably lesser amounts. The most serious nuclear accident in the history of American nuclear-power industry occurred at the Three Mile Island plant, near Harrisburg, in 1979. However, nuclear energy still provides about one-third of the state’s power generated. Hydroelectric stations and other power sources constitute only a tiny portion of the total.

Manufacturing

During Pennsylvania’s industrial heyday in the 19th and 20th centuries, the Philadelphia and Pittsburgh regions were its primary centres. Eastern Pennsylvania was noted for lighter manufacturing such as textiles, apparel, metal fabrication, and chemicals. The western part of the state focused on heavy manufacturing such as iron, steel, and machinery.

Employment in industry reached its peak of some 1.5 million in about 1970; however, that number had decreased sharply by the late 1990s. The traditional industries of textiles, apparel, iron and steel, tobacco, and leather products declined rapidly. By the early 21st century the most important industries were those producing fabricated metals, machinery, lumber, and instruments, as well as printing and publishing. Although overall employment in manufacturing had declined, the value of manufactured products continued to make a significant contribution to the state’s revenue. In the southeastern counties of Chester, Bucks, Berks, Montgomery, Lancaster, and York, high-technology industries have grown in importance.

Services

Since the mid-20th century the service sector has been a steadily increasing source of employment in Pennsylvania. In 1940 nearly half of the state’s labour force was in service jobs, and by the turn of the 21st century that proportion had increased to more than three-fourths of the workforce. The growth in service employment originally came from workers who had been active in mining and agriculture and, later, in manufacturing. Tourism is a significant source of jobs and revenue to the state and is one of the fastest-growing areas of the economy.

The number of people working in finance, insurance, and real estate grew rapidly during the 20th century, particularly in the banking and insurance fields. Real estate, security and commodity brokerages, non-depository credit institutions, and holding and investment offices were other significant employers. In the early 21st century, business services such as advertising, credit reports, and public relations were among the most rapidly growing services in the state.

Transportation

Since the colonial period, when waterways and trails provided the earliest means of travel, modes of transportation have evolved to serve the changing economy. The first major effort to improve transportation came with the building of a network of improved but unpaved roads in Pennsylvania. The extension of the Old Conestoga Road from Philadelphia to Lancaster was begun in 1721 and completed in 1733. Later that century the Lancaster Turnpike was built, roughly following the Conestoga Road; it was the country’s first turnpike. This road-building era was followed by the canal era, which dominated transportation from about 1830 to the 1850s. Canals were superseded by railroads as the primary mode of transportation until the early 20th century.

The modern period of transportation began with the widespread use of motor vehicles. As highways were built and improved, the importance of railroads declined. Today, the only interstate passenger rail service still in operation is Amtrak, which operates routes connecting Philadelphia and Pittsburgh to Washington, D.C., and linking Philadelphia with Harrisburg and cities along the Eastern Seaboard; another line travels along Pennsylvania’s Lake Erie shore on a route between Chicago and points east. SEPTA (Southeastern Pennsylvania Transportation Authority) provides regional passenger rail service around the greater Philadelphia area and extending to points in New Jersey in addition to its city bus, subway, and trolley services.

In the 20th century, Pennsylvania’s highway system was created in three stages: the establishment of the state road system, the creation of east-west and north-south U.S. highways (aided by federal funds), and the development of the interstate system. The state’s highway system, one of the most extensive in the country, includes the Pennsylvania Turnpike, a four-lane limited-access toll road (built 1939–40) joining New Jersey and Ohio; it became a model for modern superhighway construction. The turnpike is paralleled to the north by Interstate 80, known in Pennsylvania as the Keystone Shortway.

Pennsylvania has more than 100,000 miles (160,000 km) of highways; the state has primary responsibility for some two-fifths of the mileage. The remainder of its roads are controlled by counties, townships, boroughs, and cities.

Pennsylvania was an early leader in air transportation. By 1909 air shows were being staged around the state, and in 1918 the country’s first airmail service was begun between Washington, D.C., and New York City, with Philadelphia as an intermediate stop. Today, Philadelphia and Pittsburgh are the major air hubs, and Allentown (Lehigh Valley), Erie, Harrisburg, and Wilkes-Barre/Scranton have smaller international airports. Several regional airports provide commuter air service to the larger terminals. There are also some 140 public airports that do not provide regular scheduled service.