Answer:
A setting that proved to be deadly for Abraham Lincoln.
Built of metal or wood to divide. It will make us good neighbors, if you stay on your side. What is it?
Dry though I may be, I am still a sea.
Some adults still use these to count.
I can be as thin as a picture frame but my insides have many things you can see.
I am the fountain from which no one can drink. For many I am considered a necessary link. Like gold to all I am sought for, but my continued death brings wealth for all to want more.