Three separate studies are conducted regarding banks' relative efficiency. Previous to start with the development of the studies, we review the situation before and after the enactment of the Riegle Neal's. This act restricts banks from opening branches in another state. The Riegle Neal act ended up the era of state branching deregulation which started in 1970. A discussion between proponents and opponents of branching deregulation is presented. A debate between bank's efficiency and concentration before Riegle Neal is introduced in the chapter.