What was the the age of adulthood in the US before 18 become the legal age?

if you are talking about voting it used to be 21

Explanation:

The Spanish Flu Outbreak of 1918 was in effect more deadly than the Current C0vid-19 outbreak in effect rhe spanish flu killed more people world wide and in its research they found that the body would overflow in fluids to stop it therefore internally suffocating the patient what people did with the Spanish Flu is very similar to modern day socail distancing regulations to C0vid-19 the Virus also acts similar to C0VID-19 being transported through saliva and internally shuts down the body

i hope this helps