This is by no means a complete list, but here are some historic places to visit, explore, or research.
Cape May, NJ: https://www.capemayhistory.org/about-us.html
Lewes, DE: https://www.historiclewes.org/history/meet-the-past.html
Bayshore Center at Bivalve, Port Norris, NJ: https://www.bayshorecenter.org/
Delaware Bay Lighthouses: https://www.delawarebaylightkeeper-friend.org/
Cumberland County, NJ: https://cchistsoc.org
Salem County, NJ: https://www.salemcountyhistoricalsociety.com/
Fort Mott State Park, Pennsville, NJ: https://www.nj.gov/dep/parksandforests/parks/fortmottstatepark.html
Fort Delaware State Park, Delaware City, DE: https://destateparks.com/History/FortDelaware
New Castle, DE: https://newcastlecity.delaware.gov/
New Sweden Organizations:
https://www.americanswedish.org/
https://www.nps.gov/frst/planyourvisit/fort-christina.htm
Red Bank Battlefield Park, National Park, NJ: https://www.gloucestercountynj.gov/Facilities/Facility/Details/Red-Bank-Battlefield-Park-3
Fort Mifflin, Philadelphia, PA: http://www.fortmifflin.us/
Camden Shipyard Museum, Camden, NJ: https://www.camdenshipyardmuseum.org/
Independence Seaport Museum, Philadelphia, PA: https://www.phillyseaport.org/
John Fitch Steamboat Museum, Warminster, PA: https://craven-hall.org/fitch-steamboat-museum/
Burlington, NJ: http://burlingtoncountyhistoricalsociety.org/
Bordentown, NJ: https://bordentownhistory.org/
Pennsbury Manor, Morrisville, PA: http://www.pennsburymanor.org/
Roebling Museum, Roebling, NJ: https://www.roeblingmuseum.org/
New Jersey State Museum, Trenton, NJ: https://www.state.nj.us/state/museum/
Old Barracks Museum, Trenton, NJ: https://www.barracks.org/
Washington Crossing Historic Park, Washington’s Crossing, PA: https://www.washingtoncrossingpark.org/
Washington Crossing State Park, Titusville, NJ: https://www.njparksandforests.org/parks/washingtoncrossingstatepark.html
New Hope, PA: http://www.newhopehs.org/
Lambertville, NJ: https://lambertvillehistoricalsociety.org/
Easton, PA: https://www.easton-pa.com/
Delaware Water Gap National Recreation Area, NJ, PA: https://www.nps.gov/dewa/learn/historyculture/index.htm
Milford, PA: https://scenicwilddelawareriver.com/entries/historic-milford-milford-pa/936ab6cd-51a8-44b1-96d8-d5af23e40037
Port Jervis, NY: http://portjervisny.com/