What attacks by liberal/conservative groups in US have done the most damage, had most casualties?

I’m just curious. Is there a list of attacks by either left-wing/right-wing groups or individuals in the last century have caused the most damage or had the most casualties? Are there significant differences in tendencies among the two sides? By this I mean, for example, the Weather Underground warned before they attacked because, according to William Ayers, they wanted to avoid killing anyone, whereas Tim McVeigh, to my knowledge, gave no warning and killed dozens of people.

McVeigh killed 168 people.

The Oklahoma City bombing dwarfs all other American terrorist “attacks” except for 9/11.

I believe the largest terrorist attack in the USA that can be attached to a “leftist” cause would be the bombing of the LA Times building in 1910, by the McNamara brothers, which killed 21 people.

However, with people like Tim McVeigh or the McNamaras, you start to get a little fuzzy on whether those were “right wing” or “left wing” attacks. McVeigh was a paranoid nutball; the McNamaras were part of a specific union’s campaign of terrorism, not a general leftist movement, so how much they were motivated by politics and how much they were motivated by pure self-interest and the persuasion of their superiors is up for question.

It is interesting to note, though, that the labour movement strongly supported the McNamaras even after they admitted guilt, despite their having horribly murdered so many people. (And equally horrible acts by union-busting companies were also supported by political allies.) Folks who says American politics is polarized now should think about that; in 1911, people leapt to the defense of roasting innocent people alive if the roasters were on your side of a labour dispute.

An even more horrible bombing was committed (probably) by anarchists on September 16, 1920, in New York City, killing 38. Not sure where they are on the spectrum.

The Tulsa race riot may have killed as many as 300. That wasn’t specifically political in its origin or its goals, but it was certainly an enormous act of terrorism.

The East St. Louis riots of 1917managed to combine racial AND labor issues, and left 6,000 homeless and anywhere from 40 to 150 dead.

But I agree with RickJay that when you get into the motives behind terrorist attacks, it often comes down to paranoid nutjobs rather than distinct political agendas. The siege of the Branch Davidian compound in 1993 ended up with more than 70 dead. Jim Jones was responsible for the deaths of more than 900 in the Jonestown massacre. Can you define either of those groups as terrorist? Perhaps not, although the incidents sure caused a good deal of terror.

The Bath School disaster (although calling any premeditated act of murder a “disaster” risks letting the murderer off easy). From the article:

The perpetrator was school board member Andrew Kehoe, who was upset by a property tax that had been levied to fund the construction of the school building. He blamed the additional tax for financial hardships which led to foreclosure proceedings against his farm. These events apparently provoked Kehoe to plan his attack.

He killed 45 men, women and children and injured 58. His cause was lower taxes. Sounds pretty firmly in the right hand column.

Gee, I always thought the Confederate States of America put our nation in a world of hurt, if anybody ever did.