A census is what this is called. A census (depending on the type and by who is conducting it) basically counts something like the number of people in the population so that whoever is using it can get accurate results for something. Like lets say a king wanted a census of his people, animals, soldiers. He would instantly have his men count all the people in the city. They would record the amount of animals. And the same for soldiers. Then they would put all this information in a big book and keep it in the palace. It was frequently updated as people moved or died.
Lincoln was worried about Kentucky, Missouri, Maryland, and Delaware because they were all border states during the civil war. He was worried that they would transform into complete slave states. If they did, the north wouldn’t have much more land and the north would have lost the civil war. He wanted to contain them.
