The groups make up a tiny fraction of the overall 2017 report, which found a 4 percent rise in hate groups nationwide since 2016. But the SPLC says its list "understates the true level of hate in America, because a growing number of extremists, particularly those who identify with the alt-right, operate mainly online and may not be formally affiliated with a hate group".
The SPLC identified 954 hate groups in the United States past year, an increase from the 917 it had documented in 2016, the group said in a report released on Wednesday.
Fewer hate groups were active in Philadelphia previous year even they continued to increase at the national level, according to the Southern Poverty Law Center.
The group said the number of hate crimes spiked from the corresponding period of 2016, which was the worst year for anti-Muslim incidents since the civil rights organization began its current documenting system in 2013.
"President Trump in 2017 reflected what white supremacist groups want to see: a country where racism is sanctioned by the highest office, immigrants are given the boot and Muslims banned", said Heidi Beirich, director of the SPLC's Intelligence Project.
The four active groups in 2017 include three black nationalist organizations - the Nation of Islam, the Israelite School of Universal Practical Knowledge and the Israelite Church of God in Jesus Christ. However, the number of neo-Nazi groups rose to 121 up from 99 in 2016.
The report found a steep drop in the number of Klan groups, from 130 to 72.
The SPLC also identified 689 anti-government groups in 2017, up from 623 in 2016.
"President Trump's first year in office proved to be just as racially divisive as his campaign - but even more consequential", the SPLC said in its "The Year in Hate and Extremism" report. She noted that such groups have usually grown in number in response to rising white supremacy.
There were 17 hate groups active in New Jersey past year, a slight increase from the 15 active groups in 2016. Though Cruz was not a member of any group, he was steeped in white nationalist and anti-Islam ideology, authoring dozens of hateful social media posts.
A separate SPLC investigation, released earlier this month, found that 43 people were killed and 67 wounded by young men associated with the alt-right over the past four years.
The black nationalist groups listed as hate groups all espouse anti-Semitic, anti-LGBT and anti-white views, Beirich said.
In May 2017, 35-year-old Jeremy Christian was arrested and charged with stabbing to death two people and injuring a third when they attempted to prevent him from hurling Islamophobic insults at Muslim passengers.
Reinvigorated white supremacists staged their largest rally in a decade - the demonstration in Charlottesville, Virginia, that left an anti-racist counterprotester dead and Trump equivocating over condemning racism. One counter protester was killed and dozens of others were injured in the ensuing clash.
"These men right's groups talk in the same way about women", Beirich said.
For the first time, the SPLC has included what it deemed "male supremacy groups" in its report.
The male supremacist movement "misrepresents all women as genetically inferior, manipulative and stupid and reduces them to their reproductive or sexual function", the SPLC said in its report.
The SPLC has been criticized by some for the way it labels groups, including by some groups that reject the "hate group" label awarded to them by the SPLC, but it is widely seen to be a leader in the field.