WASHINGTON—A day after America’s deadliest mass shooting left at least 58 dead and more than 500 injured in Las Vegas, sources close to the nation confirmed Tuesday that it had showed dozens of warning signs leading up to the massacre. “Looking back, the U.S. had so many red flags that I’m unfortunately not at all surprised this tragedy took place,” said Nebraska resident Tyler Stout, who along with 325 million of his fellow citizens observed that the country had become increasingly isolated in recent years, often making other nations uncomfortable in its presence. “America clearly had some mental health problems, and it’s spent decades stockpiling guns and ammunition. And then there were all those crazy, unhinged rants it was constantly posting on social media. I mean, this country was just a ticking time bomb.” At press time, sources close to the nation said that perhaps the most pronounced warning sign was that it had perpetrated mass shootings hundreds and hundreds of times before.