Maybe it’s already been covered but for those that think pbs is not a valid source for this stuff I doubt they will consider the FBI and DHS valid, but here are a couple of studies to consider
It’s the right wing nut jobs killing the most people and it’s not close
And the following linked article from the NIJ was removed from the government website: Domestic Radicalization, Violent Extremism, and Terrorism: The full research picture
but I found a copy here
https://www.researchgate.net/publication/382913450_Domestic_Radicalization_Violent_Extremism_and_Terrorism_The_full_research_picture
TLDR
Since 1990 far-right violent extremism clearly constitutes the predominant source of lethal domestic political violence, while far-left extremism poses a more persistent but substantially less lethal threat.
Far-right extremists have carried out far more ideologically motivated homicides than any other category, accounting for 227 events and over 520 deaths, compared with 42 far-left attacks causing 78 deaths
This disparity persists even when controlling for changes in political climate, law-enforcement posture, and online radicalization dynamics. Far-right violence—particularly white supremacist and militant nationalist violence—tends to be more lethal per incident, more likely to involve mass-casualty attacks, and more frequently directed at soft civilian targets, which amplifies its national-level threat profile.
Far left wing nuts are definitely also a problem, but much less likely to be violent. The NIJ research finds that extreme left-wing and environmental extremist movements often exhibit longer lifespans, greater ideological persistence, and higher rates of non-violent or low-level criminal activity such as property destruction, arson, and sabotage rather than homicide. Leftist movements generate sustained law-enforcement and infrastructure challenges but rarely produce the kind of sudden, high-fatality attacks that define strategic terrorism.
If the tldr is tldr:
Both sides (BOTH SIDES!!!) are a problem BUT: domestic terrorism risk is not ideologically symmetrical: while both far-right and far-left extremism warrant monitoring and prevention, the far right represents the dominant driver of lethal political violence in the United States, whereas the far left represents a chronic but comparatively lower-lethality threat.