Delaware County, colloquially referred to as Delco,; ; ; ; ; is in the Commonwealth of Pennsylvania. With a population of 576,830 as of the 2020 census, it is the fifth-most populous county in Pennsylvania and the third-smallest in area. The county was created on September 26, 1789, from part of Chester County and named for the Delaware River. The county is part of the Southeast region of the commonwealth.

Delaware County borders Philadelphia, the nation's sixth-most populous city, to its northeast. It also is adjacent to the city-county of Philadelphia County and is included in the Philadelphia–Camden–Wilmington, PA–NJ–DE–MD metropolitan statistical area. Its county seat is Media, which is located near the center of the county.

History

Delaware County lies in the river and bay drainage area named "Delaware" in honor of Thomas West, 3rd Baron De La Warr, Governor of the nearby English colony of Virginia. The land was explored by Henry Hudson in 1609, and over the next several decades, was settled and variously claimed by the Swedes, the Dutch, and the English. Its original human inhabitants were the Lenape tribe of American Indians.

Once the Dutch were defeated and the extent of New York was determined, King Charles II of England made his grant to William Penn to found the colony which came to be named Pennsylvania. Penn divided his colony into three counties: Bucks, Philadelphia, and Chester. The riverfront land south of Philadelphia, being the most accessible, was quickly granted and settled. In 1789, the southeastern portion of Chester County was divided from the rest and named Delaware County for the Delaware River.

Geography

According to the U.S. Census Bureau, the county has a total area of , of which is land and (3.5%) is water. It is the third-smallest county in Pennsylvania by area.

Delaware County is roughly diamond- or kite-shaped, with the four sides formed by the Chester County boundary to the northwest, the boundary with the state of Delaware, a portion of the "Twelve-Mile Circle") to the southwest, the Delaware River, forming the border with the state of New Jersey) to the southeast, and the city of Philadelphia and Montgomery County to the east and northeast.

The lowest point in the state of Pennsylvania is located on the Delaware River in Marcus Hook in Delaware County, where it flows out of Pennsylvania and into Delaware. The highest point in Delaware County is 500 feet at two points southeast of Wyola in Newtown Township.

Waterways in Delaware County generally flow in a southward direction and ultimately drain into the Delaware River. The waterways are, from west to east: the Brandywine River (forming a portion of the county's western boundary with Chester County), Naaman's Creek, Stoney Creek, Chester Creek, Ridley Creek, Crum Creek, Muckinipates Creek, Darby Creek and Cobbs Creek (forming a portion of the county's eastern boundary with Philadelphia). Crum Creek was dammed in 1931 near Pennsylvania Route 252 to fill Springton Lake (also known as Geist Reservoir), an approximately drinking water reservoir maintained by Aqua America, the county's largest lake.

The Trainer Refinery and the Port of Chester are located along the shores of the Delaware River.

With its location in the southeastern part of the state, Delaware County is the only county to border both Delaware and New Jersey.

Adjacent counties Montgomery County (north) Philadelphia County (northeast) Gloucester County, New Jersey (southeast) New Castle County, Delaware (southwest) Chester County (west)

Delaware County is one of four counties in the United States to border a state with which it shares the same name (the other three are Nevada County, California, Texas County, Oklahoma, and Ohio County, West Virginia).

National protected areas

First State National Historical Park (part) John Heinz National Wildlife Refuge (part)

State protected area of the county are occupied by the Ridley Creek State Park.

Demographics

2020 census

As of the 2020 census, the county had a population of 576,830. The median age was 39.4 years. 22.0% of residents were under the age of 18 and 17.3% of residents were 65 years of age or older. For every 100 females there were 92.4 males, and for every 100 females age 18 and over there were 89.2 males age 18 and over.

The racial makeup of the county was 63.7% White, 22.4% Black or African American, 0.2% American Indian and Alaska Native, 6.3% Asian, <0.1% Native Hawaiian and Pacific Islander, 2.1% from some other race, and 5.2% from two or more races. Hispanic or Latino residents of any race comprised 4.6% of the population.

99.2% of residents lived in urban areas, while 0.8% lived in rural areas.

There were 215,498 households in the county, of which 31.6% had children under the age of 18 living in them. Of all households, 46.4% were married-couple households, 17.5% were households with a male householder and no spouse or partner present, and 30.3% were households with a female householder and no spouse or partner present. About 27.4% of all households were made up of individuals and 12.2% had someone living alone who was 65 years of age or older.

There were 229,208 housing units, of which 6.0% were vacant. Among occupied housing units, 67.8% were owner-occupied and 32.2% were renter-occupied. The homeowner vacancy rate was 1.2% and the rental vacancy rate was 7.1%.

Racial and ethnic composition +Delaware County, Pennsylvania – Racial and ethnic compositionRace / Ethnicity (NH = Non-Hispanic)Pop 1980Pop 1990Pop 2000Pop 2010 Pop 2020% 1980% 1990% 2000% 2010% 2020White alone (NH)495,635470,258438,416397,424363,24989.30%85.87%79.59%71.10%62.97%Black or African American alone (NH)49,54460,68879,070108,231127,0558.93%11.08%14.35%19.36%22.03%Native American or Alaska Native alone (NH)3795665296746760.07%0.10%0.10%0.12%0.12%Asian alone (NH)4,2209,84018,02226,14436,3170.76%1.80%3.27%4.68%6.30%Native Hawaiian or Pacific Islander alone (NH)x included in the Asian category in the 1980 Censusx included in the Asian category in the 1990 Census94114133xx0.02%0.02%0.02%Other race alone (NH)1,0233015517252,5960.18%0.05%0.10%0.13%0.45%Mixed race or Multiracial (NH)x not an option in the 1980 Censusx not an option in the 1990 Census5,8149,13020,032xx1.06%1.63%3.47%Hispanic or Latino (any race)4,2065,9988,36816,53726,7720.76%1.10%1.52%2.96%4.64%Total555,007547,651550,864558,979576,830 100.00%100.00%100.00%100.00%100.00%

2000 census As of the 2000 census, there were 550,864 people, 206,320 households, and 139,472 families residing in the county. The population density was . There were 216,978 housing units at an average density of . The racial makeup of the county was 80.3% White, 14.5% African American, 0.1% Native American, 3.3% Asian, <0.1% Pacific Islander, 0.6% from other races, and 1.2% from two or more races. 1.5% of the population were Hispanic or Latino of any race. 24.6% were of Irish, 17.5% Italian, 10.1% German and 6.7% English ancestry.

There were 206,320 households, out of which 31.5% had children under the age of 18 living with them, 50.8% were married couples living together, 12.9% had a female householder with no husband present, and 32.4% were non-families. 27.6% of all households were made up of individuals, and 11.6% had someone living alone who was 65 years of age or older. The average household size was 2.56 and the average family size was 3.17.

In the county, the population was spread out, with 24.8% under the age of 18, 8.9% from 18 to 24, 28.8% from 25 to 44, 21.9% from 45 to 64, and 15.6% who were 65 years of age or older. The median age was 37 years. For every 100 females there were 91.2 males. For every 100 females age 18 and over, there were 86.9 males.

The median income for a household in the county was $50,092, and the median income for a family was $61,590. Males had a median income of $44,155 versus $31,831 for females. The per capita income for the county was $25,040. About 5.8% of families and 8.0% of the population were below the poverty line, including 10.0% of those under age 18 and 7.1% of those age 65 or over.

Communities

Under Pennsylvania law, there are four types of incorporated municipalities: cities, boroughs, townships, and exactly one town. There are 49 municipalities in Delaware County:

City Chester

Boroughs

Aldan Brookhaven Chester Heights Clifton Heights Collingdale Colwyn Darby East Lansdowne Eddystone Folcroft Glenolden Lansdowne Marcus Hook Media (county seat) Millbourne Morton Norwood Parkside Prospect Park Ridley Park Rose Valley Rutledge Sharon Hill Swarthmore Trainer Upland Yeadon

Townships

Aston Bethel Chadds Ford Chester Concord Darby Edgmont Haverford Lower Chichester Marple Middletown Nether Providence Newtown Radnor Ridley Springfield Thornbury Tinicum Upper Chichester Upper Darby Upper Providence

Census-designated places Census-designated places are geographical areas designated by the U.S. Census Bureau for the purposes of compiling demographic data. They are not actual jurisdictions under Pennsylvania law. Other unincorporated communities, such as villages, may be listed here as well.

Ardmore (partially in Montgomery County) Boothwyn Broomall Bryn Mawr (mostly in Montgomery County) Chadds Ford (mostly in Chester County) Cheyney University (mostly in Chester County) Dilworthtown (mostly in Chester County) Drexel Hill Folsom Haverford College (partially in Montgomery County) Lima Linwood Rosemont (mostly in Montgomery County) St. Davids Village Green-Green Ridge Villanova (partially in Montgomery County) Wayne Woodlyn

Unincorporated communities

Brookline Garrett Hill Glen Mills Havertown Llanerch Oakmont Radnor Riddlewood Secane Thornton Wallingford Wawa

Population ranking The population ranking of the following table is based on the 2020 census of Delaware County.

† county seat