Pennsylvania

Delaware

576,830
2020 population
1790
first census record
24
census records

About Delaware

Delaware, Pennsylvania, first appears in the United States federal census in 1790, when it recorded a population of 9,483. At the most recent census, in 2020, its population stood at 576,830.

Its recorded population peaked at 600,035 in 1970, and has since declined by roughly 4 percent.

On the ground today, 6 documented military engagements have been recorded within the county, among them Swedish-Lenape Tinicum Conflict, Battle of the Brandywine (Colonial), Action at Chadd's Ford (Brandywine), and 98 places are listed on the National Register of Historic Places.

Population by decade

Census YearPopulationChart
2020576,830
2010558,979
2000550,864
1990547,651
1980555,007
1970600,035
1960553,154
1950414,234
1940310,756
1930280,264
1920173,084
1910117,906
190094,762
189074,683
188056,101
187039,403
186030,597
185024,679
184019,791
183017,323
182014,810
181014,734
180012,809
17909,483
Source

Population data from the United States decennial census, U.S. Census Bureau (public domain).

Battles & engagements in Delaware

Military engagements that took place in Delaware, Pennsylvania.

Swedish-Lenape Tinicum Conflict
1643
Battle of the Brandywine (Colonial)
1690
Action at Chadd's Ford (Brandywine)
1777
Battle of Brandywine Sep 11 1777
1777
Battle of Paoli (Paoli Massacre)
1777
Battle of Birmingham Hill
1777

Historic places in Delaware

National Register of Historic Places listings in Delaware, Pennsylvania.

Brandywine Battlefield
Chadds Ford
Morton, Morton, House
Norwood
North Wayne Historic District
Wayne
Chamberlain-Pennell House
Media
Chester Creek Historic District
Thornbury
Chadds Ford Historic District
Chadds Ford
Federal School
Haverford
Penn, William, Landing Site
Chester
Lower Swedish Cabin
Clifton Heights
Morton Homestead
Prospect Park
Ivy Mills Historic District
Concord Township
Tyler, John J., Arboretum
Lima
Concordville Historic District
Concordville
Chad House
Chadds Ford
Crozer, John P., II, Mansion
Upland
Lansdowne Theatre
Lansdowne
Llanerch Public School
Haverford Township
West, Benjamin, Birthplace
Swarthmore
Pusey, Caleb, House
Upland
South Wayne Historic District
Wayne
Thunderbird Lodge
Rose Valley
Albertson, Henry, Subdivision Historic District
Lansdowne
Concord Friends Meetinghouse
Concordville
Kuerner Farm-Wyeth, Andrew, Studio
Chadds Ford Township
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Other counties in Pennsylvania

Explore census history and historic records for more Pennsylvania counties.

LehighLuzerneLycomingMcKeanMercerMifflinMonroeMontgomeryMontourNorthamptonNorthumberlandPerryPhiladelphiaPikePotterSchuylkillSnyderSomersetSullivanSusquehanna
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Everything a full report reveals about Delaware County, Pennsylvania

This page charts the census history of Delaware County, Pennsylvania. A full Aubrey report for an address here pulls together everything the historical record holds about the ground, from the earliest settlement to the twentieth century:

Overview
An interactive map of the location with historic sites, battles and Native heritage plotted, and its full story era by era.
The Land
The historic sites and place names around the location, and how this land was settled and used.
Geology
The bedrock beneath the site, its age and rock type, reaching back millions of years.
LiDAR Terrain
Laser-scanned terrain that reveals earthworks and old features hidden in the landscape.
Conflict & War
The battles, raids and skirmishes fought near here, across every era of American conflict.
The Civil War
The Civil War on this ground, 1861 to 1865: who held it, and the battles, camps and regiments nearby.
The Soldiers
The men who marched from here in the Civil War, named and traced where the record allows.
Native Heritage
The Native nations who held this land, mapped across time from before European contact to today.
Settlement
Who claimed and held this ground, from Indigenous homelands through the colonial powers to the United States.
The Community
How the town grew, who came, and what kind of place it became, traced through the census record.
Rivers & Rail
The rivers, canals and railroads that connected this place between 1830 and 1911.
Notable People
The people born, buried or genuinely tied to this exact place, with their stories.
Historical Maps
Historic maps of the location layered over how it looks today.
Finds & Access
Museum objects tied to the area, and the laws on searching, collecting and access here.
Literature
The old books, county histories and archives that mention this place, quoted with their sources.
Spotlight
A deep dive into the most remarkable, lesser-known history of the place, traced back to the record.
Points of Interest
The most significant historic sites and landmarks near the location, and why they matter.
Timeline
The whole story of the location told era by era, from first peoples to the present day.
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Frequently asked about Delaware

When does Delaware first appear in the US census?
Delaware, Pennsylvania first appears in the federal census in 1790, with a recorded population of 9,483.
What is the population of Delaware?
At the most recent federal census (2020), Delaware had a recorded population of 576,830.
When did Delaware's population peak?
Delaware's recorded population peaked at 600,035 in 1970.
Were any battles fought in Delaware?
6 documented military engagements took place in Delaware, including Swedish-Lenape Tinicum Conflict, Battle of the Brandywine (Colonial), Action at Chadd's Ford (Brandywine).
How many historic places are in Delaware?
98 sites are listed on the National Register of Historic Places in Delaware, Pennsylvania.
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