Missouri has the sixth-highest gun-violence rate in the nation.

It hasn't always been that way. In 2001, including the District of Columbia, the state was ranked 17th in the nation in gun violence. The state hovered at that range, fluctuating between 15th and 17th, until early this decade, when it began to climb the list.

Earlier this month, the Regional Gun Violence Research Consortium published data that spans 2001-17. The organization — which is a consortium of six states and Puerto Rico whose goal is to disrupt the cycle of firearm-involved mass shootings, homicides, suicides and accidents — pointed out while some states have been able to reduce gun violence, Missouri and Alaska have had significant increases in their numbers over the years.

It's difficult to pinpoint what has caused the recent increase in gun violence in the state. However, there are certain geographic areas that statistically have higher numbers of incidents than others, according to Nicholas Simons, project coordinator at the Rockefeller Institute of Government. The institute coordinates the consortium. Researchers use population-adjusted rates (such as the population per 100,000 even though some areas may not have 100,000 residents) to fairly compare geographies with different population totals.

Otherwise, it's more difficult to compare urban and rural areas.

"We have noticed that on the homicide front, the population-adjusted numbers are higher in urban areas," Simons said. "Suicide numbers are higher in rural states."

For example, suicides are high in Montana, Alaska and Wyoming.

"Missouri is relatively high in both categories," Simons said. "That's unique. Missouri is kind of a mix of very rural areas with urban centers."

In 2001, the state had 13.1 firearm-related deaths per 100,000 population. In 2017, it had 21.5 per 100,000 population. That is an increase of 64 percent.

Arkansas is the only neighboring state with a similar rate of gun deaths in 2017. The state saw 20.3 gun deaths for every 100,000 population that year — an increase of 33 percent over 2001, when it was 15.3 deaths per 100,000.

Nationally — and in both states — the trend showed slight increases over the years, but around 2014, the numbers started climbing steeply.

States with the lowest ratios of gun violence deaths — Hawaii, New York, Massachusetts, Connecticut, New Jersey and California — bucked the trend and generally reduced their firearm-related deaths.

The jump in numbers around 2014 happened to some extent nationally, Simons said.

"I can't pinpoint what the 2014 jump is from," he said. "That's a general trend across the country, not just Missouri."

He added although each of the states has different laws, there's no way to prove they significantly affect gun deaths.

The consortium does suggest gun deaths may be reduced using comprehensive background checks for purchasers of firearms, prohibitions of gun ownership for people with histories of violence and extreme risk protection order laws — which allow removal of firearms from an individual who, after due process, is deemed a threat to themselves or others.

The consortium published its findings in a policy brief titled "What are the most effective policies in reducing gun homicides?" The research takes advantage of data collected for a research project at the Boston University School of Public Health and funded through the Robert Wood Johnson Foundation's Evidence for Action Program.