Andrew Johnson served as the 17th US president, and given that not much happened during his tenure, he is not as well-known as the other presidents that have been featured on today's list. He served a single term between the years of 1865 and 1869. He was working as vice president when Abraham Lincoln got assassinated, which made him move up to the position of president.
Johnson started his office as the Civil War concluded, meaning he had an easier time being in office than some of his predecessors. As president, he favored a quick restoration of the seceded states to the Union - he had a vision where America would get reunited again, and continue its existence as a prosperous nation - something that he achieved, as everyone today agrees.