At least 75 homegrown violent extremists were found to be operating across the United States in 2015, with the largest portion of these individuals pledging allegiance to the ISIS terror group, according to recent figures published by New Jersey’s Office of Homeland Security and Preparedness.

The largest number of homegrown extremists were caught providing material support to various terror organizations, while at least 21 percent of the terrorists were found to be planning attacks in the United States, according to the figures.

Another 10 percent successfully carried out terror attacks in California, New York, Tennessee, and Massachusetts, according to the data, which shows that the New York City area was home to the largest number of violent extremists.

Violent extremists were found be operating across the continental United States, including California, Texas, Missouri, Illinois, and states along the East Coast, according to the data, which confirms separate reports showing that there were more domestic terror-related arrests in the United States than at any time since the 9/11 attacks.

The figures come amid what some experts describe as an unprecedented rise in the number of foiled terror plots in the United States.

Congressional attempts to investigate the immigration histories of at least 113 foreign-born individuals snagged on terror charges since 2014 have been stymied by the Obama administration. There remain at least 1,000 open investigations into ISIS members residing in the United States.

Officials with New Jersey’s homeland security agency determined that radicalized extremists have demonstrated a continuing ability to operate across the United States, prompting concern from some terrorism experts who warn that the American homeland remains highly vulnerable to violent extremists.

"In 2015, [homegrown violent extremists] demonstrated an ability to operate in New Jersey and throughout the United States while connecting with like-minded individuals online and acting independently from organized terrorist groups," New Jersey’s homeland security agency stated in a brief of the latest terror figures. "Since late 2014, a variety of radical groups such as the Islamic State of Iraq and Syria (ISIS) and al-Qaeda in the Arabian Peninsula (AQAP) have encouraged [extremists] to attack in their home countries."

At least 87 percent of these terrorists are connected to ISIS, while the rest have aligned themselves with the al Qaeda-affiliated Al-Nusra Front and other Salafi jihadi groups.

The data shows that 23 of the 75 extremists discovered by authorities were either plotting attacks on the United States or caught after successfully conducting them, according to the figures.

A portion of these individuals, at least 4 percent, has fled overseas, the data shows. The rest were arrested or killed by authorities.

Nearly half of the 75 extremists attempted in some way to travel overseas, in many cases to receive training or resources from foreign terror groups.

Federal and local authorities continue to disrupt terror plots across America.

At the same time, the Obama administration is preparing to resettle at least 10,000 Syrian refugees in the United States in fiscal year 2016 by shortening the security screening process from around two years to about three months. Around 85,000 refugees will be resettled in the U.S. in total this fiscal year.

The plan has ignited further concerns about the possibility that some refugees also have ties to terror groups.

"Even after the terror attacks in Paris, San Bernardino, and Brussels, we still have so-called ‘experts' telling us that the terror threat is overblown," said Patrick Poole, a counterterrorism and national security analyst with Unconstrained Analytics. "But all of the indicators say the threat is escalating."

Intelligence reports show that more than 40,000 individuals from 120 different countries have traveled to fight in war-torn Syria, with at least 250 known suspects from the United States, Poole noted.

"There are two dozen reported cases of terrorists traveling among Syrian immigrants, adding yet another dimension to the threat," Poole said. "To ignore or dismiss the indicators of the metastasizing terror threat would be criminally negligent."

Michael Rubin, a former Pentagon analyst and expert on rogue regimes, warned that the domestic terror threat will continue to grow so long as U.S. officials continue to dismiss the problem.

"Home-grown extremism is accelerating and those around Obama are more interested in attacking those calling attention to the problem rather than the actual terrorists," Rubin said.

"Globalization isn't a one-way street. And so the problem of homegrown extremism isn't going away," he said. "The question now is whether the U.S. response is going to be denial or handicapped by political correctness. If there's one lesson historians should take from the Obama administration, it is that declaring a problem non-existent or contained doesn't make it so."

"Al Qaeda didn't die with Bin Laden, no matter how much the journalists seeking Obama’s good graces desired," Rubin added. "The Islamic State wasn't a mere JV terror team, as not only Iraq and Syria, but also Egypt, Libya, and Afghanistan know too well."