Alan Marcus and Walter Woodward have been studying the role of Confederate monuments and other nostalgia in American memory.

“Historical monuments are intended to be timeless, but almost all have an expiration date,” they wrote. “As society’s values shift, the legitimacy of monuments can and often does erode.”

This is because monuments, including the names of U.S. military bases, reveal the values of the time in which they were created and advance the agendas of their creators.