Includes most places I've been in 20 years of life, such as major cities and regions (or attractions), anything designated by the National Park System, state parks and monuments, etc. I'm 21, but I haven't been traveling in the past eight months/since I turned 21 five months ago because of the pandemic, so these are all places I've been as a 20-year-old.
This list doesn't include some places that I've technically been, because I was either too young to totally remember, the town/village was too small, was there for a very short amount of time (like I was in the Bahamas for an hour on a cruise stop when I was eight), or wasn't in the actual city itself (such as San Diego or Phoneix because I haven't explored the actual cities).