1755, April 20. British Maj. Gen. Edward Braddock (1695-1755) and troops encamped at Rockville area.
1776. Montgomery County created from Frederick County, named for Revolutionary War Gen. Richard Montgomery (1738-1775).
1787. First Courthouse erected at Rockville.
1791, Dec. 19. Maryland ceded Montgomery County land (Georgetown) for federal District of Columbia.
1794. Hyattstown Mill constructed.
1808. Brookeville incorporated.
1809. Rockville Academy chartered.
1809-1823. Nathan Loughborough (1772-1848) of Montgomery County served as U.S. Comptroller of the Treasury.
1814, Aug. 26-27. President James Madison, Attorney General Richard Rush, and other Cabinet members sought refuge at Brookeville, following British attack on Washington, DC.
1828-1848. Chesapeake and Ohio Canal constructed.
1830. Josiah Henson (1789-1883) from slavery on Isaac Riley's farm (North Bethesda) escaped to freedom in Canada.
1833. Monocacy Aquaduct at Dickerson, design and construction overseen by Benjamin Wright (1770-1842).
1833. Seneca Aquaduct opened at Seneca.
1840. Second courthouse completed at Rockville.
1860. Rockville incorporated.
1861-1864, Sept. Montgomery Blair (1813-1883) of Silver Spring served as U.S. Postmaster General.
1861, June-1862, March. Union Brig. Gen. Charles P. Stone's corps of observation at Poolesville.
1862, Sept. 5. Confederate cavalry brigades under Gen. Wade Hampton and Gen. Fitzhugh Lee camped around Barnesville.
1862, Sept. 8. Skirmishes at Poolesville and Hyattstown between Union and Confederate cavalry.
1862, Sept. 9. Skirmishes at Beallsville and Barnsville between Union and Confederate cavalry.
1862, Sept. 13. Union Gen. Winfield Scott Hancock's II Corps camped near Barnesville on route to Antietam.
1862, Oct. 10-12. Gen. J.E.B. Stuart's cavalry rode through Washington, Frederick and Montgomery counties during raid into Pennsylvania.
1863, June 26. Union Maj. Gen. Joseph Hooker's headquarters established at Poolesville during Gettysburg campaign.
1863, June 27-28. Union troops marched through Barnesville on route to Gettysburg.
1863, June 28. Confederate Gen. J.E.B. Stuart and his cavalry occupied Rockville on route to Gettysburg.
1863, June 28. Confederate Gen. Jubal Early's cavalry arrested Union supporters at Rockville.
1863. Fort Alexander, Fort Ripley, and Fort Franklin, protecting Washington, DC, waster system since 1861, were connected by earthworks and renamed Fort Summer at Bethesda.
1864, July 11-12. Confederate Gen. Jubal Early had his headquarters at Silver Spring.
1867. Poolesville incorporated.
1873. Metropolitan Branch of Baltimore & Ohio Railroad ran from Washington, DC, northwest through Montgomery County to Point of Rocks.
1878. Gaithersburg incorporated.
1880, July 24. John Diggs lynched in Montgomery County.
1888. Barnesville incorporated.
1890. Takoma Park incorporated.
1891. Third courthouse built at Rockville.
1892. Laytonsville incorporated.
1892. Francis G. Newlands (1846-1917) developed Chevy Chase.
1894. Kensington incorporated.
1898. Garrett Park incorporated.
1899, Oct. 18-1915. Gaithersburg Latitude Observatory as part of International Polar Motion Service began to measure variations in latitude caused by earth's wobble on its solar axis.
1904. Glen Echo incorporated.
1906. Somerset incorporated.
1910. Chevy Chase Village incorporated.
1916, May 19. Blair Lee III (1916-1985), Acting Governor of Maryland, born in Silver Spring.
1918. Washington Suburban Sanitary Commission created to improve water and sewer service in Montgomery and Prince George's counties.
1918. Town of Chevy Chase incorporated.
1924. Floods destroyed much of Chesapeake & Ohio Canal.
1927. Maryland-National Capital Park and Planning Commission formed for Montgomery and Prince George's counties.
1931. Fourth courthouse constructed at Rockville.
1932. "Bonus army" traveled through Maryland.
1932-1982. Gaithersburg Latitude Observatory resumed operations
1937. Washington Grove incorporated.
1937. Montgomery County equalized pay for black and white teachers.
1938. Federal government began moving National Institutes of Health to site near Bethesda.
1938. Silver Spring Shopping Center opened.
1938, June. National Institutes of Health established in Bethesda.
1939, Feb. Chesapeake & Ohio Canal opened as national park.
1942, Aug. Naval Medical Center dedicated, Bethesda.
1946, Sept. Montgomery County Junior College (now Montgomery College) opened, first in State.
1948. Montgomery became first Maryland county to adopt charter form of government ("home rule"), with a County Manager and County Council.
1949, Jan. 18. First County Council took office.
1949, Jan. 21-1953, Jan. 20. Dean Acheson (1893-1971) of Montgomery County served as U.S. Secretary of State.
1960, June 30. Sit-ins and picket lines challenged segregation policies at Glen Echo Park.
1961, March 4. Sargent Shriver of Montgomery County named first Peace Corps director.
1962. Baltimore City and Montgomery County adopted open accommodations.
1962. Silent Spring, by Rachel Carson (1907-1964) of Montgomery County, published.
1964, Aug. 16. Capital Beltway (I-495) opened, encircling Washington, DC, by passing through Maryland's Prince George's and Montgomery counties, and Virginia.
1965. Washington Suburban Transit Commission established for Montgomery and Prince George's counties.
1968. County adopted a County Executive and County Council form of government.
1968. Marshall W. Nirenberg (1927-2010), National Institutes of Health, won Nobel Prize in Medicine.
1968, July 19-20. Eunice Kennedy Shriver (1921-2009) of Montgomery County opened first International Special Olympics in Chicago.
1969, Jan. 21-1973, Sept. 3. William P. Rogers (1913-2001) of Montgomery County served as U.S. Secretary of State.
1970. First County Executive elected.
1970. Julius Axelrod (1912-2004), National Institutes of Health, won Nobel Prize in Medicine.
1972. Christian B. Anfinsen (1916-1995), National Institutes of Health, won Nobel Prize in Medicine.
1972. Sargent Shriver of Montgomery County, Democratic Party candidate for U.S. Vice-President, ran with George McGovern.
1976. D. Carleton Gajdusek (1923-2008), National Institutes of Health, won Nobel Prize in Medicine.
1976. Washington Metro, rapid transit system for national capital area, opened to link stations in Maryland, Washington, DC, and Virginia.
1981. Judicial Center constructed at Rockville.
1982. Village of Chevy Chase, Section 3 incorporated.
1982. Village of Chevy Chase, Section 5 incorporated.
1985. Martin?s Additions incorporated.
1993. Chevy Chase View incorporated.
1996. North Chevy Chase incorporated.
1997. Unification of Takoma Park into Montgomery County.
1997. William D. Phillips (1948-), National Institute of Standards and Technology, won Nobel Prize in Physics.
1999. Gunter Blobel (1936-), Howard Hughes Medical Institute, won Nobel Prize in Medicine.
2000. Eric R. Kandel (1929-), Howard Hughes Medical Institute, won Nobel Prize in Medicine.
2002, Sept. 10. Electronic voting machines first used during primary elections in four counties (Allegany, Dorchester, Montgomery, Prince George's).
2004, March 2. Electronic voting system used during primary elections at polling places and for absentee ballots in all counties and Baltimore City.
2005, Sept. 29. John G. Roberts, Jr. (1955-) of Montgomery County began to serve as Chief Justice, U.S. Supreme Court.
2007. Mario R. Capecchi (1937-), Howard Hughes Medical Institute, won Nobel Prize in Medicine.
2008. Roger Y. Tsien (1952-), Howard Hughes Medical Institute, won Nobel Prize in Chemistry.
2009. Thomas A. Steitz (1940-), Howard Hughes Medical Institute, won Nobel Prize in Chemistry.
2009. Jack W. Szostak (1952-), Howard Hughes Medical Institute, won Nobel Prize in Medicine.
2011, Feb. 23. First segment of Intercounty Connector (MD Route 200), the State's first all-electronic toll road, opened for Montgomery and Prince George's counties. Covering seven miles, this segment links Gaithersburg with Olney.
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