A state’s laws governing the sale, ownership and use of guns – or its lack of such laws – are a powerful influence on rates of suicide and firearms-related homicide there, new research shows.

A study published Monday in the journal JAMA Internal Medicine finds that suicides carried out with a firearm are less common in states with strict gun laws than in states where gun laws are more relaxed.

In fact, the states with the strictest gun laws were found, on average, to have lower overall suicide rates as well. That is evidence that troubled people without access to a gun will not necessarily find another way to take their own lives, according to the authors of the study, a team from Weill Cornell Medical Center and Columbia University in New York and the University of Pennsylvania.

None of the 48 continental United States is an island unto itself. When it comes to rates of gun-related homicides, the strength or weakness of a state’s gun strictures mattered a lot – but so did the strength or weakness of gun laws adopted by that state’s neighbors. Strict or not, the effects of gun laws in a neighboring state cross state lines into counties that adjoin it, the study authors reported.

Across the country, the highest rates of homicides committed with a gun were found in counties in states with relaxed gun laws and close to other states with few limits on guns.

A neighboring state could exert a positive influence as well. In counties in a state with lax gun laws, gun-related homicides were lower when a closely neighboring state had adopted very strict gun laws.

The authors of the new study discerned these patterns by combing through death records kept by the Centers for Disease Control and Prevention and organized by cause of death and county. They identified gun-related suicides and homicides by county between January 2010 and December 2014. Then, they looked at how those county-level firearms death rates aligned with the level of gun laws in place within the state and across neighboring states’ lines.

The new research underscores the power of state gun laws at a time when federal lawmakers have declined to take action on firearms. Calls for legislation at the state level, especially in Florida, have escalated in the wake of a Feb. 14 school shooting that claimed 17 lives in Parkland, Fla.

The states are a patchwork of laws governing sale, licensure, carriage and use of guns. And like pretty much everything in the U.S. economy, firearms flow freely across state lines.

The distribution of death rates from firearms, however, is far from uniform across the country. Guns were the cause of death in 3.4 in every 100,000 deaths in Massachusetts that year, according to the CDC. In Louisiana, guns caused 21.3 of every 100,000 deaths, and 23.3 of every 100,000 deaths in Alaska.

This has prompted a new line of firearms injury research focusing not just on whether and how well state gun laws work to reduce gun injuries, but how a neighboring state can support or undermine a state’s efforts to curb gun violence.