In 2016, then-candidate Donald Trump tweeted that “inner-city crime is reaching record levels.” He was off by a long shot: violent crime had ticked up in some cities that year, but rates were still nowhere near the astronomical levels of the early 1990s.

For Trump, it was one in a litany of mischaracterizations, exaggerations, and outright falsehoods. But innumeracy about violent crime has long plagued policy discussions and news reporting, and that public ignorance is exactly what Patrick Sharkey, a New York University sociology professor, wants to combat with a new online tool. American Violence, developed by Sharkey and a team of social scientists, is an online portal that enables readers to easily explore murder rates and trends in American cities by culling the most up-to-date data from reliable local sources.

While the FBI collects city-level murder figures in its annual Crime in the United States reports, its numbers are at least a year old and scattered across documents that take some effort to collate. American Violence is to crime wonks what a stock app is to market watchers. The site assembles and translates publicly available but abstruse information into an interface that doesn’t take specialized training to navigate.

“Researchers, politicians, journalists, policymakers, and the public can all know that they’re going to the single place to get the definitive word on how violence is changing and how much violence there is in different cities across the country,” Sharkey told The Trace.

With easier access to the data, “people will be able to have a more informed public debate about the problem of violent crime,” Sharkey said.

In launch form, American Violence is powered by the latest available homicide data from 82 of the country’s largest 100 cities, which Sharkey and his team pull directly from city police departments and other vetted sources every month. Users can focus on a single city or compare statistics across the country in a map view. Murder rates can be viewed over a single stretch of time or compared over multiple periods. Sharkey believes the latter feature can inject badly needed nuance into narratives around urban violence.

“Confusion between short-term trends and long-term trends is hugely destructive and problematic and dangerous,” he said.

American Violence offers a granular look at urban murder rates.

A research brief drawing on the site’s data spells out how the ways in which crime rates are framed can shape or distort our understanding of them. The paper analyzes urban murder rates in the United States during three periods. Over the long-term, between 1991 and the present, rates plunged dramatically. Between 2014 and the present, there was a significant uptick in violence, but murders never came close to the “record levels” described by Trump and his political allies. “The recent rise of violence has barely made a dent in the long-term crime decline,” the authors state, driving home the importance of situating recent fluctuations in a broader historical context.

The third time period, spanning April 2017 to March 2018, indicates that murder rates are again on the decline over the previous 12 months. The authors stress that the short-term movement isn’t enough to draw conclusions about the long-term trend, but it does indicate that the medium-term spike has abated.

Between 2016 and 2017, murder rates declined in eight of the ten largest U.S. cities.

Sharkey and his collaborators plan to continue expanding the amount and type of information provided by American Violence. Next on the roadmap: neighborhood data. Users will be able to zoom into individual cities and examine trends at the community level, a feature which Sharkey hopes will help local policymakers design and gauge the impact of initiatives to reduce violence. After that, the team intends to expand the map to include shooting incidents, as well.

“Violence is the fundamental challenge of American cities,” said Sharkey. “Cities don’t work when public spaces are unsafe. The very idea of city life doesn’t work.” While American cities are no longer the sites of pervasive violence they were in the 1980s and early 1990s, work remains to be done in the pockets where murder rates remain elevated.

“Now we have to focus on the places where it still is true,” Sharkey said, “and really try to make sure that there’s no city where violence dominates public spaces.”