2) What was a special characteristic of the border states?

considerable anti-slavery element was present within the state

Explanation:

Another characteristic of a border state would be that a considerable anti-slavery element was present within the state which meant that, while the economy of the state would not have been heavily tied to the institution of slavery, the population of the state could present hard political problems for the Lincoln.

Straddling the North and South states, were the Border States; Delaware, Kentucky, Maryland, and Missouri ... The President's attempts to disprove the loyalty of these Border States prevented the government from abolishing slavery in them, fueling Lincoln's critics.