1661, May 16. At Spesutia Island, peace treaty with Susquehannocks signed by Gov. Philip Calvert.
1740, Oct. 31. William Paca (1740-1779), signer of Declaration of Independence, born in Abingdon.
Capt. John Smith historical marker along Bush River, Abingdon, Maryland, June 2015. Photo by Sarah A. Hanks.
1775, March 22. "Bush Declaration" signed, Bush River, Harford County, patriots called for independence.
1781, Sept. 9. Jean Baptiste Donatien de Vimeur, Count de Rochambeau's French troops camped at Havre de Grace en route to Yorktown.
1782, Aug. Count de Rochambeau's French troops camped near Abingdon on return march north from Yorktown.
1785. Havre de Grace incorporated.
1787, Dec. Cokesbury College, first Methodist college in world established at Abingdon.
1791, March. First Courthouse completed at Bel Air.
1813, May 3. British forces under Rear Admiral Sir George Cockburn sacked and burned Havre de Grace.
1827, Nov. Concord Point Lighthouse, erected at mouth of Susquehanna River, went into service; one of oldest lighthouses in continuous operation on East Coast, oldest in continuous operation in Maryland.
Havre de Grace War of 1812 historical marker, Havre de Grace, Maryland, June 2015. Photo by Sarah A. Hanks.
1840-1894. Susquehanna & Tidewater Canal linked Havre de Grace to Pennsylvania Canal at Wrightsville, Pennsylvania.
1859. Second Courthouse constructed at Bel Air.
1864, July 10. Maj. Harry Gilmor's Confederate cavalry encamped near Joppatowne.
Harford County Courthouse, 20 West Courtland St., Bel Air, Maryland, March 2000. Photo by Diane F. Evartt.
1865, April 26. Following a 12-day manhunt, John Wilkes Booth (1838-1865) was shot and killed in Port Royal, Virginia; later buried in Green Mount Cemetery, Baltimore.
1872. Bel Air incorporated.
1892. Aberdeen incorporated.
1900, March 27. Lewis Harris lynched by masked, armed mob in Bel Air on Churchville Road.
1917, Oct. 20. Aberdeen Proving Ground, first ordinance testing center of U.S. Army, established (opened Dec. 1917).
1917, Nov. 1 Construction of plant to fill artillery shells with chemical agents [weapons] began at Gunpowder Neck Reservation (later Edgewood Arsenal), adjacent to Aberdeen Proving Ground.
1917, Dec. 14. President Woodrow Wilson issued proclamation creating chemical weapon research and development facilities at Gunpowder Neck Reservation.
1918, May. Gunpowder Neck Reservation renamed Edgewood Arsenal.
1921, Nov. 8. Mary E. W. Risteau became first woman elected to House of Delegates.
1947. The first large-scale, general-purpose electronic digital computer, ENIAC (electronic numerical integrator & computer) was delivered to U.S. Army's Ballistic Research Laboratory, Aberdeen Proving Ground.
1955-1975. Edgewood Arsenal conducted classified chemical agent experiments on soldiers.
1957, July 1. Harford Junior College (later Harford Community College) founded.
1967. Maryland joined Susquehanna River Basin Commission.
1971. Ladew Topiary Gardens, Monkton, opened to public.
1971, July 1. Edgewood Arsenal merged with Aberdeen Proving Ground.
1974-1978. Charles B. Anderson, Jr. (Democrat), County Executive.
1978-1982. J. Thomas Barranger (Democrat), County Executive.
1980, Oct. 21. Northeast Maryland Waste Disposal Authority created.
1982-1990. Habern W. Freeman (Democrat), County Executive.
1986. Havre de Grace Decoy Museum opened.
1990-1998. Eileen M. Rehrmann (Democrat), County Executive.
1992. Ballistic Research Laboratory succeeded by Army Research Laboratory, headquartered in Adelphi, Prince George's County.
1998-2005. James M. Harkins (Republican), County Executive.
2002, June 18. Aberdeen Ironbirds played first game at new Ripken Stadium in Aberdeen.
2004, March 2. Electronic voting system used during primary elections at polling places and for absentee ballots in all counties and Baltimore City.
2005, July 7 - 2014, Dec. 1. David R. Craig (Republican), County Executive.
2014, Dec. 1-. Barry Glassman (Republican), County Executive.
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