Coplay is a borough in Lehigh County, Pennsylvania, United States. Coplay's population was 3,348 at the 2020 census. It is located six miles (10 km) northwest of Allentown. The borough is part of the Lehigh Valley metropolitan area, which had a population of 861,899 and was the 68th-most populous metropolitan area in the U.S. as of the 2020 census.

Coplay is located at 40°40′14″N 75°29′43″W / 40.67056°N 75.49528°W / 40.67056; -75.49528 (40.670521, -75.495395). According to the U.S. Census Bureau, the borough has a total area of 0.6 square miles (1.6 km), of which 0.6 square miles (1.6 km) is land and 0.04 square miles (0.10 km) (3.08%) is water. Coplay is situated along the Lehigh River, approximately 5 miles (8.0 km) north of Allentown.

Coplay was part of the 400 acres (1.6 km) of land John Jacob Schreiber bought from the William Penn's heirs in 1740. It was initially known as Schreibers and later was known as the Lehigh Valley, because of Lehigh Valley Iron Furnaces were located here. Lehigh Valley was then changed to Coplay, derived from "Kolapechka", the son of the Indian chief Paxanosa, who lived at the head of the creek near Schnecksville. Coplay seceded from Whitehall Township in 1869 and was incorporated as a borough on April 7, 1869.

Coplay gradually changed from a farming area into an industrial community, starting with the founding of the Thomas Iron Company, which attracted laborers and built homes for them. When the Iron Company was liquidated, other industries gradually came to Coplay, including the Cement Mill, the Silk Mill, the Cigar Factory, and Knitting Mill. Coplay became a melting pot of many nationalities. The Pennsylvania Dutch and Germans were initially drawn to the area for its agricultural promise. The growth of the iron industry attracted immigrants from Ireland. Then, in the early 1900s, the Cement Mills attracted immigrants from Austria, Hungary, Czechoslovakia, Poland, and Ukraine.

On April 7, 1969, the borough celebrated its centennial anniversary. A celebration was held from June 15–21 in the town. In 1980, in recognition of historical value, Coplay Cement Company Kilns was added to the National Register of Historic Places.

Historical population

Census	Pop.	Note	%±
1870	728		—
1880	774		6.3%
1890	880		13.7%
1900	1,581		79.7%
1910	2,670		68.9%
1920	2,845		6.6%
1930	3,279		15.3%
1940	3,109		−5.2%
1950	2,994		−3.7%
1960	3,701		23.6%
1970	3,642		−1.6%
1980	3,130		−14.1%
1990	3,267		4.4%
2000	3,387		3.7%
2010	3,192		−5.8%
2020	3,348		4.9%
Sources:

As of the 2000 census, there were 3,387 people, 1,431 households, and 953 families residing in the borough. The population density was 5,373.1 inhabitants per square mile (2,074.6/km). There were 1,484 housing units at an average density of 2,354.2 per square mile (909.0/km). The racial makeup of the borough was 96.84% White, 1.56% African American, 0.09% Native American, 0.32% Asian, 0.53% from other races, and 0.65% from two or more races. Hispanic or Latino of any race were 2.27% of the population. Coplay has the second highest rate of Austrian ancestry in the United States, at 10.6%.

There were 1,431 households, out of which 28.8% had children under the age of 18 living with them, 49.3% were married couples living together, 13.5% had a female householder with no husband present, and 33.4% were non-families. 29.3% of all households were made up of individuals, and 14.4% had someone living alone who was 65 years of age or older. The average household size was 2.34 and the average family size was 2.90.

In the borough, the population was spread out, with 23.0% under the age of 18, 5.3% from 18 to 24, 29.9% from 25 to 44, 20.9% from 45 to 64, and 20.9% who were 65 years of age or older. The median age was 40 years. For every 100 females there were 86.2 males. For every 100 females age 18 and over, there were 83.3 males. The median income for a household in the borough was $38,679, and the median income for a family was $46,278. Males had a median income of $31,519 versus $24,983 for females. The per capita income for the borough was $18,580. About 5.6% of families and 7.0% of the population were below the poverty line, including 13.8% of those under age 18 and 5.3% of those age 65 or over.

United States presidential election results for Coplay, Pennsylvania

Year	Republican		Democratic		Third party(ies)
	No.	%	No.	%	No.	%
2020	874	49.80%	854	48.66%	27	1.54%
2016	779	51.45%	669	44.19%	66	4.36%
2012	574	41.12%	801	57.38%	21	1.50%
2008	563	37.43%	912	60.64%	29	1.93%
2004	637	41.72%	883	57.83%	7	0.46%

The Borough of Coplay is served by the Whitehall-Coplay School District. Coplay students in grades nine through 12 attend Whitehall High School.

As of 2007, there were 11.18 miles (17.99 km) of public roads in Coplay, all of which were maintained by the borough. Main thoroughfares through Coplay include Second Street and Chestnut Street.

• Saquon Barkley, professional football player, Philadelphia Eagles, and 2018 NFL Offensive Rookie of the Year

• Official borough website