“How do people assign meaning and weight to past events? Sociologists have coined the term “collective memory” to describe it. And it turns out that collective memory doesn’t just dictate the way groups recall the past en masse. Rather, wrote Jeannette A. Bastian, an event’s “memory trajectory” also influences the ways archivists preserve history—and opens up opportunities to contextualize and document more than just an event.” Erin Blakemore tells us more.