How many U.S. Presidents have anarchists killed?

Answer 1

Obviously not enough

Answer 2

"Not enough" is a correct answer, but in case you are still looking for a more quantitative measurement, the answer seems to be one - Leon Czolgosz shot President McKinely in 1901. Other presidential assasins were motivated by various other political beliefs.

When the view is expanded to well known would-be assasins, we might arguably include Guiseppe Zangara, based on his alleged* statements while on trial, "I have the gun in my hand. I kill kings and presidents first and next all capitalists, " and,  "Hoover and Roosevelt — everybody the same."

While Zangara, so far as I can tell never professed anarchism, his analysis seems to fall within the realm of affinity with-.

Comments

Oops - should've had the following at thge bottom:
* This is based on my previous knowledge of US History (moderate, but not scholarly), and a quick study of internet resources about known presidential assasinations. I chose to not include a Symbionese Liberation Army sympathizer, or the suspected assasinations where there is no proof or suspects. All the same, for actual assasinations, we are responsible for fully a quarter of them!

Answer 3

Sante Geronimo Caserio stabbed Marie François Sadi Carnot, the President of the Third French Republic, in the chest. It was a fatal attack.

“I heard the ‘Marseillaise’ and the cries of ‘Viva Carnot!’ I saw the cavalry come up. I understood that the moment had come and I held myself ready. On seeing the President's carriage I drew my dagger and threw away the sheath. Then, when the carriage was passing close by me, I sprang forward to the step, supported myself by resting my left hand on the carriage, and with my right hand buried the dagger in the President's breast.[1]

[…] The Board of Pardons decided against all appeals for clemency on August 14. Caserio was executed by guillotine in Lyon at precisely 5am, August 16, 1894.[1] In front of the guillotine, he exclaimed ‘Coraggio cugini—evviva l' anarchia!’ (‘Courage, cousins—long live anarchy!’)”

That makes two.

EDIT: Didn't see the bit about “U.S.” presidents. Meh.