The Anti-Defamation League said it logged a total of 5,125 cases last year, compared with 2,724 in 2019. Its study focused on paper propaganda and signs, not online messages.
The tally was the highest since the ADL, which monitors the activities of domestic and international hate groups, began tracking such materials in 2016.
Jessica Reaves, a director of ADL's Center on Extremism, said that far-right groups use posters and fliers to draw attention to online materials.
She said the groups also believe that physical propaganda frightens minority groups, adding: "They want people to feel fear."
While the materials surveyed came from 30 different organizations, ADL said more than 90% came from the Patriot Front, the New Jersey European Heritage Association or the Nationalist Social Club.
The most prolific was the Texas-based Patriot Front, which ADL said was behind 80% of all the incidents.
Formed in 2017, the group sought to build its "brand" last year by avoiding white supremacist language and symbols, instead favoring phrases such as "America First," "United we stand," and "Two Parties. One Tyranny," ADL said.By contrast, the New Jersey European Heritage Association, which operates in 23 states, included overtly antisemitic and anti-African American messages in its materials.