Terrorism is not a new thing, but it certainly has a new face.
Here's some historical acts most people don't know about.
The phone monitoring isn't working (see post 2002 terrorist acts).
4 May 1886 Chicago, Illinois Bomb thrown during labor rally at Haymarket Square kills 7 policemen, many injured; police fire into crowd, killing 4; 8 anarchists accused
30 Dec 1905 Frank Steunenberg, former Idaho governor, killed by bomb
1 Oct 1910 Bombing by labor activists at The Los Angeles Times building caused partial collapse of the building; two bombs at other locations were defused
14 Oct 1912 Former President Theodore Roosevelt shot and injured in attempted assassination outside hotel en route to speech
On November 24, 1917 a bomb thought to have been planted by anarchists killed nine police officers in Milwaukee, Wisconsin.
29 Apr 1919 mail bomb sent to home of senator Thomas Hardwick explodes, injuring a housekeeper and the senator's wife
On June 2, 1919, anarchists were suspected of setting off a series of bombs in eight cities, including Washington, D.C., where a bomb partially destroyed the home of Attorney General A. Mitchell Palmer.
On September 16, 1920, an explosive-laden wagon exploded on Wall Street, across from the headquarters of J.P. Morgan & Company, killing 40 and wounding 300.
Edit: removed individual nutcase murders, for the most part they weren't 'terrorism'.