This SPLC chart shows such groups increased from 48 in the year 2000 to 233 in 2017. The latest report puts the 2018 total at 264, a 450% increase over the year 2000.
The new SPLC report says:
Black nationalist hate groups make up about a quarter of the total number of hate group chapters in 2018. This sector has been growing for several years, and continued to do so last year, with an increase from 233 chapters in 2017 to 264 in 2018.The SPLC writes this at the end of its permanent page on Black Nationalists:
The racism of a group like the Nation of Islam may be the predictable reaction to white supremacy. But if a white group espoused similar beliefs regarding African Americans and Jews and, few would have trouble describing it as racist and anti-Semitic. If we seek to expose white hate groups, we cannot be in the business of explaining away the black ones. [emphasis added]However, the new report includes this line:
Unlike white nationalist groups, however, they have virtually no supporters or influence in mainstream politics, much less in the White House.While Black Nationalist groups may have little open support in mainstream politics, groups such as the Congressional Black Caucus have long-standing ties to Louis Farrakhan for which they have never been fully called to account. (I have written extensively of those CBC-Farrakhan ties in the Wall Street Journal and National Review Online.)
Violent white nationalism is clearly a problem in the US as the recent arrest of a Coast Guard lieutenant who had planned a massacre demonstrates. But a growing Black Nationalist threat (see this 2017 SPLC report: Return of the Violent Black Nationalist) also clearly exists as groups such as Louis Farrakhan's Nation of Islam, as the SPLC itself puts it, continue to spread "antisemitic, anti-LGBT and anti-white" messages of hate.