Notable things that happened in history involving the USA on April 18th:
1906 - San Francisco Earthquake : An earthquake, measuring 7.8 on the Richter scale, shook the town of San Francisco , California and Thirty thousand homes were either partially or wholly destroyed and an estimated 3,000 are reported dead. The earthquake set off a series of fires which swept through the city.
1958 - U.S.A. Satellite Map : The US Military hinted that it will be possible with satellites orbiting the earth to pinpoint any place on the earth and make a detailed drawing including unfriendly countries ( So that is where Google Maps started ).
1978 - Panama Canal to be given to Panamanian Contro : The US Senate has backed a treaty to transfer the Panama Canal to the control of Panama. The building of the Panama Canal was started by the French in 1880 but in 1904 the US took over the construction of the canal which was completed 10 years later.
1983 - Lebanon Car Bomb US Embassy: A
car bomb is used as a terrorist weapon successfully in an attack on the U.S. embassy complex in Beirut, Lebanon killing 12 people. The terrorist a member of Islamic Jihad drove at high speed up the main drive of the consulate in a truck containing 500 kg of high explosive exploding in front of the U.S. embassy.