Vacant buildings are many things: signs of decay, eyesores and dangerous. They might also hold a strong relationship to crime.
According to frequently updated data provided by Open Baltimore, there is a strong correlation between vacant buildings and certain crimes, such as shootings and homicides.
Common assault, a physical attack, increases from neighborhood to neighborhood as the number of vacant houses increases — a trend shared with crime in general. And it does so at a much more pronounced rate than other crimes.
Shootings, homicide and aggravated assault all have a stronger correlation, or direct connection, than common assault, but have a slower trend, or rate by which the two are related, than common assault as well.
Studies have linked vacant buildings and urban crime. Lin Cui, a professor at the University of Pittsburgh, looked at changes in crime totals when a foreclosed building becomes vacant. He found that violent crime rises by an average of 15 percent within 250 feet of the property, as soon as it became vacant.
While Cui also looked at property crime in his study, he acknowledges that the effect of vacant buildings on property crime is not as well measured by his study. His research shows that a longer vacancy has a stronger impact on crime and that foreclosures alone do not drive up crime.
Cui's work builds off a 1993 study by William Spelman, which showed a doubling of crime on blocks with "open abandoned buildings," those that can be entered without the use of force. Spelman suggests the securing of abandoned buildings is an effective means to reduce crime.
"Vacant buildings are a magnet for all kinds of negative behavior, such as homelessness and drug dealing," said Jeffrey Ian Ross, a criminologist at the University of Baltimore.
Ross cautions that the data source is a cause for concern — since police can only publish data based on reported crimes, those that go unreported might change the relationship. For example, in an area where reporting crime is easier, there can appear to be more crime.
"The greater the number of people looking for something, the more you'll find of it," Ross said.
Studies also have suggested links between other indicators and illegal behaviors.
The "broken window" and "urban tree" theories connect different indicators with crime, namely signs of disrepair and the distribution of trees.
Broken window policing involves stricter enforcement of minor quality of life crimes, such as vandalism, with the goal of reducing more serious crime. New York City police credit the tactic for the city's decrease in crime, but research finds no evidence to support these claims.
The role of trees in deterring crime is based on a study by the U.S. Forest Service, which focused on Baltimore. The study, which found that neighborhoods with more trees have less crime, met with mixed reception, with some welcoming the study and others doubting it.
Nancy La Vigne of the Urban Institute sees the relationship between vacant buildings and crime as a chicken-and-egg situation.
"Looking at these visual measures of communities is a valid approach," La Vigne said. However, she is concerned by attempts to pin crime to a single indicator.
The Washington-based institute studied possible connections between foreclosures and crime, but found no relationship. La Vigne said that many variables are also at play and it's hard for researchers to pin some down.
Other variables include data not contained in the city's part one crime data, a category established by the FBI that encompasses the most serious crimes. Part two offenses, which cover all other felony offenses, include drug distribution and gang activity.
Still, securing vacant structures or strictly enforcing quality of life crimes may not be the ultimate solution to crime.
"I don't know you would find any credible criminologist who would support such a claim," said La Vigne. "When cracking down on low level offenses, you have to take account of the relationship between the police and the community — broken window policing can undermine the legitimacy of the police."
One House at a Time, a court-appointed receiver of vacant and blighted buildings, auctions off vacants to qualified groups and individuals, including non profits. The organization mainly handles residential properties, but has auctioned a few commercial properties. It works independently of the city and developers.
Part of the organization's mission, which predates the city's Vacants to Value program, is to create safer and more stable neighborhoods through the rehabilitation of certain buildings.
"Any time that a vacant house is brought back and occupied, the area around the house should be safer," said founding board member Bill Romani.