In truth, the extremely low first marriage ages of the post-war
years were an aberration. Contrary to popular myth in the "old
days" men didn't get married at all that young of an age and
women didn't all get married on their 18th birthday. It's in the
1950-1970 era that the marriage age shrunk radically, with men
and women marrying at more similar ages. The key difference now
is that both male and female first marriage ages are going up in
tandem. The age gap between the genders shrunk in the 50-70
years as both men and women were marrying earlier, and then the
gap remained relatively small as members of both genders began
to delay marriage until a later time.