The Chicago Tribune highlights an important fact about the Tiller assassination: this is only one in a series of more than 6,100 documented acts of violence against abortion providers since 1977:

Bombings. Butyric acid attacks. Sniper shootings. Letters filled with fake anthrax. These are some of the tactics used over the years by antiabortion extremists.

The slaying of Dr. George Tiller in his Kansas church Sunday was part of a decades-long history of domestic terrorism aimed at abortion providers, carried out by a small minority of the much broader and generally peaceful movement that opposes abortion.

The National Abortion Federation, which supports abortion rights, has documented more than 6,100 acts of violence against abortion providers in the United States and Canada since 1977. The group classifies as “violent” not only the acts of murder, attempted murder, bombing and arson, but also vandalism, burglary and stalking, among others.

Tiller’s slaying appears to be the eighth of an abortion clinic worker in the U.S. or Canada and the fourth of a doctor. A fifth doctor was shot but survived — as did Tiller in a previous attack.