White House intruders
Most White House intruders do not try to harm the President (who may not even be in residence), but are usually attempting to attract attention to their causes or ideas (e.g. Anthony Henry) or are intruding accidentally (e.g. a plane inadvertently flying into White House airspace). There have been four assassinations of U.S. presidents and many more assassination attempts. None of the assassinations occurred at the White House, and only one attempt occurred there (see below).
Extensive security measures are used to protect the White House as the official residence (Executive Residence) and office space (West Wing) of the President of the United States. Security is primarily provided by the United States Secret Service. Since the September 11, 2001 attacks, the restricted airspace above the White House has been expanded and better enforced.
Currently, a fence surrounds the White House, but it did not always exist. Though at various points since the time of Thomas Jefferson, various fences and gates were added to shape or constrain public access, greater public access to the White House grounds than was common in comparable European institutions was possible (with some restrictions) up until World War II. After World War II, public access to the White House grounds has been increasingly restricted.
During the mid-1990s, the fence was expanded by one block to move traffic farther from the White House to prevent damage from any car bomb.
Police built barricades on the streets surrounding the White House in 1983.
In November 2011, Oscar Ramiro Ortega-Hernandez was taken into custody in Indiana, Pennsylvania (near Pittsburgh, Pennsylvania) in connection with bullets fired near the White House- at least two of which impacted- on Constitution Avenue, NW (near The Ellipse and the closed Washington Monument), at least one of which was stopped by bullet-proof glass, the other having hit the exterior; it is unknown whether the White House was a target or was even involved- the President and First Lady were in Hawaii for the APEC Summit meeting at the time. A suspect was seen fleeing into Virginia from the 23rd Street, NW, entrance to the Theodore Roosevelt Bridge from an abandoned car left near there.
Successful and attempted intrusions 
Times given are local time.
- April 13, 1912 – Michael Winter
- December 21, 1922 – Paul McDaniel
- April 3, 1934 – Benoit Bousquie
- January 18, 1937 – Sam Muller
- February 17, 1974 – Robert K. Preston
- February 1974 – Samuel Byck (unsuccessful assassination attempt)
- December 25, 1974 (7:07 am) – Marshall H. Fields
- November 26, 1975 and again December 6, 1975 – Gerald B. Gainous
- July 27, 1976 – Chester Plummer
- April 7, 1976 – Andrea Copsey
- December 1, 1976 – Steven B. Williams
- October 1978 – Anthony Henry
- March 3, 1984 – David Mahonski
- January 28, 1985 – Robert Latta
- March 15, 1985 – Chester Ramsey
- August 21, 1986 (1:15 am) – Rosita Bourbon
- November 21, 1987 – Mike Davis
- December 5, 1988 – Patrick Jude Laughlin
- 1991 – Gustav Leijohhufvud
- September 12, 1994 – Frank Eugene Corder
- October 29, 1994 – Francisco Martin Duran
- May 24, 1995 – Leland William Modjeski
- October 4, 1996 – Leah Persons
- February 8, 2001 – Robert W. Pickett
- October 4, 2005 – Shawn A. Cox
- April 9, 2006 – Brian Lee Patterson (third time)
- October 13, 2006 – Alexis Janicki
- March 16, 2007 – Catalino Lucas Diaz
- June 9, 2009 – Pam Morgan
- November 24, 2009 – Carlos Allen; Michaele and Tareq Salahi (see 2009 White House gatecrash incident)
- Public Report of the White House Security Review, chapter 4, "The Evolution of Presidential Security" (1995).
- "White House Secure". Sun Sentinel. May 25, 1995. Retrieved November 29, 2009. "The radar on the White House roof has been upgraded to protect against kamikaze planes, Pennsylvania Avenue has been blocked to foil car bombers – and still a gunman can clamber over the wrought-iron fence and sprint to within 50 feet of the president's windows. The response from the men and women who guard the White House: Unless you want to turn the president's house into a walled-off fortress, there just isn't much you can do about "jumpers" – except try to stop them on the lawn."
- Grass, Michael (November 16, 2011). "Oscar Ramiro Ortega-Hernandez Arrested: Alleged White House Shooter In Custody In Pennsylvania". Huffington Post.
- "Intruder in White House Is Arrested After Forcing His Way In to See Taft". The New York Times. April 13, 1912. Retrieved February 5, 2009.
- PUBLIC REPORT OF THE WHITE HOUSE SECURITY REVIEW, Federation of American Scientists
- "Officers Arrest a Man Outside White House". The New York Times. November 22, 1987. Retrieved February 5, 2009.
- Schmitt, Eric (October 30, 1994). "Gunman Shoots at White House From Sidewalk". The New York Times. Retrieved February 5, 2009.
- Sanger, David (February 8, 2001). "Officer Shoots Armed Man Near White House Fence". The New York Times. Retrieved February 5, 2009.
- "Trespasser Scales White House Fence". The New York Times. Associated Press. December 5, 2005. Retrieved December 1, 2009.
- Williams, Clarence; Weil, Martin (October 15, 2006). "Man Arrested at White House". Washington Post. Retrieved December 1, 2009.
- "66-year-old man leaps White House fence". USA Today. March 16, 2007. Retrieved February 1, 2009.
- Ward, Jon (June 9, 2009). "Fence-jumper immediately apprehended at White House". Washington Times. Retrieved December 1, 2009.
- "Feds: Couple crashed Obama's state dinner". CNN. November 26, 2009. Retrieved November 26, 2009.
- Cristina Corbin (November 26, 2009). "Who Are the White House Party Crashers?". Fox News.