The current opioid epidemic is the deadliest drug crisis in American history. Overdoses, fueled by opioids, are the leading cause of death for Americans under 50 years old — killing roughly 64,000 people last year, more than guns or car accidents, and doing so at a pace faster than the H.I.V. epidemic did at its peak.

President Trump declared the opioid crisis a “public health emergency” on Thursday, though he did not release additional funding to address it. Had he declared it a “national emergency,” as he promised to do in August, it would have led to the quick allocation of federal funds.

The New York Times has been covering the outbreak — from when it started bubbling up in towns around the United States years ago to now, as it decimates communities and families.

Here is a roundup of our best reporting on the epidemic, including short answers to hard questions about it.