I think that what adcoms really want to see is that you've taken the time to interact with them as much as you possibly can.
If you can't visit the campus then you should send an email to the adcom introducing yourself, telling them how interested you are in their school, and asking some questions (be sure that you couldn't find the info on the web easily). Be aware that all of your correspondence will be kept on file so make sure you email is of high quality.
You should also try to interact with alumni in your area if possible, and with some current students. When I was researching My schools I tried to get in contact with some of the clubs that I might be interested in joining. I found that to be a great way to have some informal chats about the school, make some friends before you ever show up on campus, and have something else to talk about in your interview.
Finally, if your target school has an outreach event somewhere that it would be possible for you to get to then you should make every effort to attend.
Adcoms want you to be committed to their school, they want to be sure that if you are offered a place then you'll accept.
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