The Lehigh Valley has historically been a global leader in steel and other heavy manufacturing industries, which represented a considerable portion of its employment and economic production for most of the 20th century.

[6][7] In March 2024, the Lehigh Valley was named the nation's top mid-sized market for economic development by Site Selection magazine based on its number of projects that met criteria for job creation, investment, and size over the previous year.

[10] In 1737, sons of provincial Pennsylvania founder William Penn acquired much of the Lehigh Valley in the Walking Purchase during the colonial period.

As early as June 21, 1774, patriot forces in Allentown began meeting to formulate resistance plans to British colonial governance.

[12] Following the signing of the Declaration of Independence, the Colonial British government in Allentown began dissolving and these patriot militias seized control, pressuring Tories out of the region.

In recognition of the strong pro-revolutionary sentiment in the region, Easton was one of only three designated locations, along with Philadelphia and Trenton, New Jersey, where the Declaration was read aloud in public for the first time on July 8, 1776 at noon.

Washington and his staff stopped at the foot of Lehigh Street at a large spring on what is the present-day Wire Mill Arboretum in Allentown.

During the late summer and early fall of 1861, members of this unit and other volunteers from within and beyond the Lehigh Valley came together to form the 47th Pennsylvania Infantry Regiment, which was established on August 5 and later proved influential in expanding the Union Army's reach into the Deep South, permitting it to launch successful attacks against Confederate positions in the Battle of St. Johns Bluff in 1862 and throughout the Red River campaign in the Trans-Mississippi theater and Sheridan's Shenadoah Valley campaign across Virginia in 1864.

The company developed into the nation's second-largest manufacturer of steel, and its steel was used in developing many of the nation's earliest and largest infrastructure and building projects, including the Empire State Building, Madison Square Garden, and Rockefeller Center in New York City, Merchandise Mart in Chicago, the George Washington, Verrazzano, and Golden Gate Bridges, and warships and other military equipment that proved essential in American-led victories in both World Wars.

[19] During the 20th century, Bethlehem Steel's ascent was prominently associated with the emergence of the U.S. as both a world leader in global manufacturing and as the world's largest economy, and its late 20th century downfall has often been cited as an example of one of the nation's most prominent first stumbling points in the face of growing foreign trade competition and other economic challenges that contributed to the nation's emergence of its Rust Belt.

The company abruptly reduced operations, resulting in considerable Lehigh Valley layoffs and a dramatic related economic downturn in the region.

The Lehigh Valley has four distinct seasons, which typically include hot and humid summers, cold winters, and short and mild springs and falls.

Beginning in the 1980s, however, the region's manufacturing sector declined rapidly as a result of foreign competition, trade practices, operational costs, regulations, and other factors.

In the late 20th century, however, a variety of factors, including the practices of foreign competitors, began eroding Bethlehem Steel's once historical global leadership in steelmaking.

In the early 2000s, seeking to replace the heavy manufacturing companies that had been the region's foundation for decades, the Lehigh Valley began developing other economic sectors, including financial services, health care, life sciences, and technology.

The Lehigh Valley also began emerging as a national warehouse and distribution hub, due in part to its proximity to many of the largest U.S. markets and relatively lower operating costs compared to other Northeast U.S.

[42] Several large companies from China and Germany have invested tens of millions of dollars into developing significant operations in the Lehigh Valley, which has generated thousands of new jobs in the region.

[44] The Lehigh Valley is one of the fastest-growing and largest economies in Pennsylvania and the United States with a total GDP of $55.7 billion (as of 2023) that saw a four percent increase between 2022 and 2023 alone driven by strong manufacturing, financial, health care, and professional services industry segments.

[45][46] It was named in March 2024 as the top mid-sized market in America by Site Selection Magazine for economic development based on the number of projects that met certain criteria for job creation, investment and size in 2023.

[47] It is centrally located in the Northeast megalopolis with ease of access and close proximity to several of the largest U.S. markets, population centers, airports, terminals, railways, and seaports, including the New York City and Philadelphia metropolitan areas.

[51][57] Large companies such as Amazon.com have praised the Lehigh Valley for its commitment to business support, infrastructure investment, and incentive programs, citing these as major reasons for their continuing expansions and increased hiring in the region[58][59] and Allegiant Air, a low-cost budget airline, opened a new flight base at the Lehigh Valley International Airport in February 2020, noting the area's rapid growth, lower operational business costs, and its proximity to popular destinations as significant reasons for expanding their Lehigh Valley International Airport flights.

In September 2018, FedEx Ground constructed their largest distribution hub in the country near Lehigh Valley International Airport at a cost of $335 million.

[69] Additionally, Ocean Spray, a popular maker of juice drinks and other fruit products, produces 40 percent of its total national beverage volume at its Lehigh Valley plant in Breinigsville.

Multiple movies have been fully or partially filmed in the Lehigh Valley, including M. Night Shyamalan's Glass in 2019, indie dark-comedy Getting Grace starring Daniel Roebuck, Taylor A. Purdee's folk rock musical Killian & the Comeback Kids, and others.

[75] The following year, in 2013, following the Garrett Reid overdose and the hiring of new head coach Chip Kelly, the Eagles chose to move their training camp to the NovaCare Complex in South Philadelphia.

In 2003, CNN aired a highly critical documentary on the center, Achieving the Perfect 10, which depicted its as a hugely demanding and excessively competitive training program.

[80] The stadium is the home field for the Lehigh Valley IronPigs, the Triple-A affiliate of the Philadelphia Phillies of Major League Baseball.

[83] Lehigh University's Paul Short Run is held annually at the Goodman Cross Country Course; participation has climbed to over 5,000 runners spread throughout 14 college and high school races.

[89] Das Awkscht Fescht, an antique car festival, is held annually the beginning of August in Macungie's Memorial Park.

[103] Lehigh Valley AVA, which was designated an official American Viticultural Area in March 2008, includes 230 acres (93 ha) of vineyards planted to several Vitis vinifera and French-American hybrid grape varieties.