The New York-based advocacy group's data showed 5,125 cases reported in 2020, compared to 2,724 in 2019, even though incidents on college campuses dropped by more than half, possibly due to COVID-19 restrictions.
Critics say white supremacism got a boost from US President Donald Trump's recently-ended presidency though he denied racism and said he was smeared by political opponents.
His successor, President Joe Biden, has ordered an assessment of the risk of domestic terrorism in the wake of the Jan. 6 attack on the US Capitol by Trump supporters, some of whom displayed supremacist symbols.
The ADL said in a report on its website that supremacist propaganda appeared in every US state except Hawaii last year, with the highest levels of activity in Texas, Washington, California, New Jersey, New York, Massachusetts, Virginia and Pennsylvania.
The ADL said the largest white supremacist event of 2020 was a flash demonstration in Washington, DC, in February, before the pandemic became the dominant national issue and the election campaign heated up.
The vast majority of the propaganda in 2020 — 80% — came from a Texas-based white supremacist group called Patriot Front, which employs red, white and blue in its materials and plays on traditional American patriotic language.
One of the group’s stickers reads “Life, liberty and the pursuit of victory.” Another features a map of the continental U.S. and says “Not stolen, conquered.” A third says “America first,” the slogan with anti-Semitic roots that was adopted and popularized anew by former president Donald Trump.
In November, the group held a 100-person march down a main boulevard in Pittsburgh, a city that has become a pilgrimage spot for white supremacists two years after the deadly 2018 synagogue shooting there.
Just like in 2019, the only state without reports of white supremacist propaganda was Hawaii.
"The barrage of propaganda, which overwhelmingly features veiled white supremacist language with a patriotic slant, is an effort to normalize white supremacists' message and bolster recruitment efforts while targeting minority groups including Jews, Blacks, Muslims, non-white immigrants, and the LGBTQ community," it said.
United Nations Secretary-General Antonio Guterres warned last month that white supremacy and neo-Nazi movements were becoming a "transnational threat" and had exploited the coronavirus pandemic to boost their support.
US Representative Jackie Speier sent a letter earlier this year to Biden urging him to issue an executive order identifying white supremacy and violent extremism as a threat to national security.Ben Sales contributed to this report.