To calculate this, Everytown relies on a five-year-average of data from the CDC, whose National Vital Statistics System contains the most comprehensive national data, currently available through 2015."Fatal Injury Reports," Injury Prevention & Control: Data & Statistics (WISQARS), accessed January 3 2017,' http://1.usa.gov/1plXBux']

The number of Americans injured with firearms dwarfs the number who are killed, although data to measure non-fatal shootings are less reliable. The CDC’s National Electronic Injury Surveillance System estimates the number of annual non-fatal firearm injuries based on reports from a sample of hospital emergency departments: over the last five years, there were more than 200 non-fatal firearm injuries each day."Non-Fatal Injury Reports," Injury Prevention & Control: Data & Statistics (WISQARS), accessed June 29, 2015 http://1.usa.gov/1qo12RL.

Of the 169,395 firearm deaths in the US from 2011 to 2015 (the most recent five years of data available), 105,183 (or 62 percent) were suicides. To calculate this total, Everytown relies on CDC data regarding fatal injury by intent."Fatal Injury Reports," Injury Prevention & Control: Data & Statistics (WISQARS), accessed January 3 2017,' http://1.usa.gov/1plXBux']

Rates of firearm injury death increase rapidly after age 12. And unintentional shootings of children and teens are underreported in the CDC data, possibly because of the difficulty of characterizing a child’s intent after he or she has killed himself or a playmate with a firearm. Everytown tracks unintentional shootings involving children, which occur every 34 hours, on average. School Shootings since Newtown, http://every.tw/1eh50vh

And more than half of all women killed by intimate partners in the U.S. are killed with guns.Federal Bureau of Investigation, Supplementary Homicide Reports, 2010-14, available at http://bit.ly/1yVxm4K. Over the last five years of available data, 55% of women killed by intimate partners (including same-sex partners) were killed with guns.

An analysis of gun homicide rates in developed countries— those considered “high-income” by the World Bank — found that the United States accounted for 46 percent of the population but 82 percent of the gun deaths.Erin Grinshteyn and David Hemenway, "Violent Death Rates: The US Compared with Other High-income OECD Countries, 2010," American Journal of Medicine, 2015. The World Bank defines a high-income country as one with a gross national income per capita greater than $12,736. The study analyzed data from populous (>1 million inhabitants), high-income countries that were members of the Organization for Economic Co-Operation and Development (OECD) in 2010. Additionally, the study excluded Iceland and Luxembourg from the broader OECD for having very small populations, and also excluded Greece and Switzerland for not using detailed ICD-10 codes.

According to a study by the Department of Justice, between 1994 and 2014, federal, state, and local agencies conducted background checks on more than 180 million firearm applications and denied 2.82 million gun sales to prohibited people. Assuming a similar rate of the period 2015-16, to date the background check system has likely blocked nearly 3 million firearm sales to prohibited people.US Department of Justice, Bureau of Justice Statistics, Background Checks for Firearm Transfers, 2013-14 - Statistical Tables, by Jennifer C. Varberg, Ronald J. Frandsen, Joseph M. Durst, Trent D. Buskirk, and Allina D. Lee (June 2016), http://bit.ly/2av5tvL.

Black Americans make up 14 percent of the U.S. population U.S. Census Bureau. 2010. http://www.census.gov/prod/cen2010/briefs/c2010br-06.pdf but are victims of more than half of all gun homicides.“Fatal Injury Reports," Injury Prevention & Control: Data & Statistics (WISQARS), accessed January 25, 2015, http://1.usa.gov/1plXBux.

A case-control study of 11 cities found that in a domestic violence situation, the perpetrator’s access to a gun increased the odds of femicide by more than five times (adjust OR=5.44, 95% CI = 2.89, 10.22).Jacqueline C. Campbell, Daniel Webster, and Jane Koziol-McLain, "Risk Factors for Femicide in Abusive Relationships: Results from a Multisite Case Control Study," American Journal of Public Health 93, no. 7 (June 2003): http://1.usa.gov/1osjCet.

Both the Centers for Disease Control and Prevention (CDC) and the FBI collect data on firearm homicides — the former from medical examiners and the latter from local law enforcement. Each data set has distinct advantages and flaws. The CDC’s National Vital Statistics System records a higher percentage of all firearm deaths but fails to capture details about their circumstances, including the relationship of the perpetrator to the victim. This makes it unsuitable for measuring gun violence between people of certain relationships.

In contrast, the FBI’s Supplementary Homicide Reports (SHR) include details on the perpetrator and weapon but are more likely to be missing records because the FBI relies on police departments to voluntarily submit their homicide data on an annual basis. Despite these gaps, SHR data are utilized widely in the criminology community. The SHR do not include data from the state of Florida. Everytown obtained data directly from the Florida Department of Law Enforcement. Women killed by former dating partners (as opposed to current dating partners) are not categorized in the Florida data and are not included.James Alan Fox, “Missing Data Problems in the SHR: Imputing Offender and Relationship Characteristics,” Homicide Studies 8, no. 214 (2004); and Catherine Barber and David Hemenway, “Underestimates of Unintentional Firearm Fatalities: Comparing Supplementary Homicide Report Data with the National Vital Statistics System,” Injury Prevention 8 (2002).