Updated

Fifty people are dead after a man opened fire early Sunday inside a gay nightclub in Orlando, and dozens more were left wounded. Authorities are calling the shooting an act of domestic terrorism. Here’s The Washington Post’s main news story.

The shooting would be by far the deadliest in the past 34 years. As America grapples with another mass shooting, we’re certain to face questions about the country’s unique gun culture and the prevalence of gun violence. There are some perhaps surprising developments — gun ownership in the United States is declining overall, for instance. But while mass killings have occurred with increasing frequency in recent years, support for gun rights is still resolute in America.

Aerial footage shows police responding to a shooting at Pulse nightclub in Orlando on Sunday, June 12 where a gunman wielding an assault-type rifle and a handgun took hostages. Approximately 50 people were killed. (Reuters)

Here are answers to a few questions you might have about guns and mass shootings:

How common are mass shootings in the United States?
How many people own guns?
Are mass shootings becoming more common?
When were deadliest shootings in U.S. history?
Is the United States an especially violent place, compared to other countries?
Where is violence most common in America?
Is the number of guns related to the number of homicides?
Is gun control reduce gun-related deaths?
Is there public support for gun control?
Do most Americans support gun control policies?
How do mass shootings affect public opinion on this issue?

 1. Shooting sprees are not rare in the United States. 

Mother Jones has tracked and mapped shooting sprees over the three decades since 1982. The magazine counted 62 mass shootings from 1982 through 2012, using the definition of 4 or more people killed in a public space in a seemingly indiscriminate killing. The magazine updated its numbers to include three or more people killed for calculations starting 2013, and since then there have been 18 more mass shootings through February of this year, not including the Orlando killings.

In most cases, the Mother Jones staff found, the killers had obtained their weapons legally:


2. Gun ownership in the United States is declining overall, but nearly a third of households still have a gun.

The General Social Survey has been asking Americans whether they have a gun in their home for decades, and 2014 essentially tied the record low level of gun ownership reached in 2010. As you can see the chart below, 31 percent of adults reported having a firearm in their household. That is 17 percentage points below the peak rate of gun ownership, from 1977 to 1980.

Survey data released in 2014 by the Pew Research Center broke down the demographics of gun ownership more broadly, as Pew's analysts wrote:

Overall, about a third of all Americans with children under 18 at home have a gun in their household, including 34% of families with children younger than 12. That’s nearly identical to the share of childless adults or those with older children who have a firearm at home.

The new research also suggests a paradox: While blacks are significantly more likely than whites to be gun homicide victims, blacks are only about half as likely as whites to have a firearm in their home (41% vs. 19%). Hispanics are less likely than blacks to be gun homicide victims and half as likely as whites to have a gun at home (20%).

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Pew found that gun ownership is concentrated among older adults, rural residents, and whites, especially white Southerners. Whites in the South are more likely to own guns than whites in other regions.

The shooter in Sunday morning's incident has been identified as Omar Mateen, 29, of Fort Pierce, Fla. He was killed by police at the club in Orlando.

 3. Active shooter events have become more common in recent years.

A report published by the FBI in 2014, studying active shooting situations between 2000 and 2013, found that these kinds of incidents have been happening more and more frequently. In the first seven years of the study, there were an average of 6.4 active shootings per year, while in the last seven years of the study, there were 16.4 incidents per year.

Active shooters are defined by federal agencies as "an individual actively engaged in killing or attempting to kill people in a confined and populated area." (This is different from mass killings, which are episodes in which three or more people are killed, according to the FBI. While many active shooting incidents wind up being mass killings, more than half of the episodes in the FBI study did not meet that definition.)




 4. Of the 12 deadliest shootings in the United States, at least half happened after 2007.

As this map by The Washington Post shows, several of the deadliest shootings ever in the United States have happened in just the past few years -- including the massacres at Sandy Hook Elementary School in Newtown, Conn. and at Virginia Polytechnic Institute and State University in Blacksburg. These were the two shootings that claimed the most lives, and the third deadliest shooting was in 1991 in Killeen, Tex.

 5. America is an unusually violent country. But we're not as violent as we used to be.


Kieran Healy, a sociologist at Duke University, made this graph of deaths due to assault in the United States and other developed countries. We are a clear outlier -- along with Estonia and Mexico. Yet this country is a far less violent place than it was 40 years ago, with the rate of deaths due to assault declining by roughly half.

As Healy writes, "The most striking features of the data are (1) how much more violent the U.S. is than other OECD countries (except possibly Estonia and Mexico, not shown here), and (2) the degree of change—and recently, decline—there has been in the U.S. time series considered by itself."

 6. The South is the most violent region in the United States.


In a subsequent post, Healy looked at deaths due to assault in different regions of the country. Just as the United States is a clear outlier in the international context, the South is a clear outlier in the national context:

 7. More guns tend to mean more homicide.

The Harvard Injury Control Research Center assessed the literature on guns and homicide and found that there's substantial evidence that where there are more guns, there are more homicides. If guns are available, it is more likely that a violent dispute will become a deadly one, and that a criminal with the intent to kill can find the means to do so.

This holds true whether you're looking at different countries or different states, and it's also true when you take into account factors such as the age of the population, the number of people living in cities, and the overall violent crime rate. Click here for the research.

 8. States with stricter gun control laws have fewer deaths from gun-related violence, but the connection is complicated.

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In 2011, economist Richard Florida dove deep into the correlations between gun deaths and other kinds of social indicators. Some of what he found was, perhaps, unexpected: Higher populations, more stress, more immigrants, and more mental illness were not correlated with more deaths from gun violence. But he also found that states with tighter gun control laws appear to have fewer gun-related deaths.

"The map overlays the map of firearm deaths above with gun control restrictions by state," Florida wrote in 2012. "It highlights states which have one of three gun control restrictions in place - assault weapons' bans, trigger locks, or safe storage requirements. Firearm deaths are significantly lower in states with stricter gun control legislation. Though the sample sizes are small, we find substantial negative correlations between firearm deaths and states that ban assault weapons (-.45), require trigger locks (-.42), and mandate safe storage requirements for guns (-.48)."

An important caveat is that correlation does not equal causation, and passing additional gun-control laws might not substantially reduce gun violence. For example, it could be that the states with stricter gun control laws are also states in which gun ownership is less prevalent. Since there are fewer gun owners in these states, there might also be fewer people advocating for gun rights. Because there are fewer guns in these states, there could also be fewer homicides, but the number of homicides could be related to the number of guns and not directly to the state's laws.

Click here for more on the complicated relationship between gun control and violent crime.

 9. Gun control, in general, has not been politically popular -- and its popularity has been declining lately.

Since 1990, Gallup has been asking Americans whether they think gun control laws should be stricter.

The answer, increasingly, is that they don't.

"Less than half of Americans, 47%, say they favor stricter laws covering the sale of firearms, similar to views found last year," Gallup says. "But this percentage is significantly below the 58% recorded in 2012 after the school shooting in Newtown, Connecticut, spurred a nationwide debate about the possibility of more stringent gun control laws. Thirty-eight percent of Americans say these laws should be kept as they are now, and 14% say they should be made less strict."

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 10. While general gun control isn't that popular, particular policies are.

While many Americans strongly support the right to bear arms, they also support specific restrictions, such as background checks, assault weapons bans and a federal database to track guns. Here's 2013 data from Pew Research Center.

FT_Gun_Proposals


 11. Shootings don't tend to substantially affect views on gun control.

That is what the Pew Research Center found after polling Americans after mass shootings in the United States. In fact, Pew reported late last year that for the first in more than 20 years, Americans showed more support for gun rights than gun control. That's what Pew found after Newtown.


And before other mass shootings, as well:

shootings and gun control views

In fact, more people say gun ownership protects people from a crime.

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This post has been adapted from previous versions, which were authored by Ezra Klein and Zachary Goldfarb, with contributions from Mark Berman.