(NewsNation) — In America’s heartland, Iowa, Kansas and Nebraska are among the states with dozens of cities not reporting their data, according to data analysis by The Marshall Project.

Although the New York Police Department is listed as one of the law enforcement agencies accused of not reporting its 2021 crime data to the FBI, criminologists say the NYPD still has a very good idea of what’s happening crime-wise in New York City because of its own sophisticated system of tracking crime.

But the FBI says the only way it can truly assess how bad crime is nationwide is through law enforcement agencies’ full cooperation.

The New York City and Los Angeles police departments are among the 40% of law enforcement agencies nationwide not sharing their 2021 crime data with the FBI.

“Crime is on a lot of people’s minds, and it’s unfortunate that in 2021, we don’t have good crime data from across the country,” said data reporter Weihua Li.

Li is with The Marshall Project, a nonpartisan, nonprofit news organization that covers the country’s criminal justice system.

Li discovered what she calls a “massive gap” in crime data not being reported to the FBI.

“For example, we probably wouldn’t be able to know which city has the highest homicide rate for a while because so many of these large cities aren’t submitting info to the FBI,” Li explained.

The FBI started collecting crime data almost a century ago, asking local law enforcement agencies around the country to submit data to its “uniformed crime reporting system.”

But participation is voluntary, not a federal mandate.

As of 2018, more than 16,000 agencies were submitting data.

“The FBI announced years ago that by 2021, we won’t take data from the old system,” said Li.

The new system is called the National Incident Based Reporting System, or “NIBRS” for short. Li says she doesn’t believe agencies are intentionally concealing or underreporting their data. It’s about timing and money.

“No one could’ve foreseen the pandemic or the murder of George Floyd,” Li said that the pandemic and the social justice demonstrations kept law enforcement busy.

Also, it costs millions to transition to the new system and millions more for training and maintaining it.

“The federal government doesn’t have that many carrots or sticks to incentivize or force local agencies to report their data,” Li explained. Li said the FBI predicts cities will report more of their crime data to the FBI by the years 2025-2026.

The FBI has spent well over $150 million in the last five years helping local law enforcement make the transition to the new system.

But many agencies are still lacking the funding and manpower to make a successful transition.