How is the book best correlated to a time in history?

Tim O'Brien's novel joins two time periods, the 1960s–early-70s and the 1990s, through the device of a college class reunion.
Because the characters were all coming of age during the Vietnam War, that time permanently shaped—even warped—their perspectives. Many of the men are veterans who served for different lengths of time and had complicated recoveries including PTSD and drug addiction. Others avoided service by fleeing to Canada or other means. For the women, although they are not veterans, the men in many of their lives did serve: one became a pastor, another has struggled against and survived breast cancer.
By choosing to place the characters 31 years after graduation (relying on a small plot contrivance), the author also locates them at the turn of the millennium, a time that was fraught with anxiety and yet promised renewed hope for many. Some of the characters seem poised to embrace that challenge, while others seem trapped in a toxic past.