Mateen was armed with a pistol and an assault-style rifle, both purchased legally days before the attack despite the fact that Mateen had previously been interviewed three times by the Federal Bureau of Investigation, according to the Orlando Sentinel.
The debate about the attack -- and whether or not gun control measures could prevent similar attacks in the future -- is likely to continue through the election season.
"It seems clear that the call for 'common-sense' gun regulations will be a major issue in this year's presidential campaign, since the two candidates take such starkly opposing positions on this question," said Stephen Klineberg, founding director of the Kinder Institute for Urban Research and Rice University professor.
Nationally, stricter gun control wins slight support from the public, but it's not necessarily a high priority either, according to the Pew Research Center. In 2000, some 66 percent of respondents said it was more important to control gun ownership than protect gun rights, but that number fell to 46 percent in 2014. The most recent survey data, from July 2015, shows 50 percent favoring gun control and 47 percent saying gun rights were more important.
Support for universal background checks, however, was much stronger. Eighty-five percent of Americans supported expanding background checks for private and gun show sales, as of 2015, a number that roughly mirrors local attitudes in the Houston area. According to the annual Kinder Institute Houston Area Survey, in 2013, the last time the question was asked, roughly 87 percent of Harris County residents favored universal criminal background checks for all gun sales.
"That public preference was never translated into effective legislation," the Kinder Institute wrote at the time, "since those who were opposed to any such restrictions were more likely to advocate for that position and to vote on this one issue alone than those who were in support of 'common-sense' regulations."
The picture changes when residents were asked about a potential ban on assault weapons. In 2005, just months after the Federal Assault Weapons Ban expired, 65 percent of respondents favored such a ban. But in 2013, only 45 percent said they supported a federal law banning assault weapons.
Meanwhile, despite its reputation for being gun-friendly, a recent study found that Texas's rate of gun ownership was only slightly above the national average. The study by Columbia University researchers found that roughly 29 percent of Americans own guns, compared to roughly 36 percent of Texans. Alaska, by contrast, had the highest rate of ownership at 61 percent.
Texas has been on the forefront of the guns right issue in part because the state recently enacted legislation allowing individuals with permits to carry concealed weapons on university campuses. Since then, universities have struggled with how to manage the new law.
In May, Texas Republicans said repealing all licensing requirements for firearm owners was one of their top five priorities for the next legislative session, according to Houston Public Media. The platform adopted at the 2016 party convention opposed taxes on gun sales, gun-free zones and "all federal acts, laws, executive orders, and court orders which restrict or infringe on the people’s right to keep and bear arms."
That platform isn't in line with the views of Harris County residents, based on polls.
"Like most Americans, Houston area residents, even in red-state Harris County, are generally in favor (often strongly so) of some modest restrictions on access to guns," Klineberg said. "But (so far, at least), the fear of 'gutting' the 2nd Amendment has galvanized the opposition to ensure the defeat of any restrictions that might be the first steps toward registration and even eventual confiscation."