The above is a surname distribution map produced by RootsMap. This endeavors to show the place of birth of people before the major advent of the Industrial Revolution, after which greater migration took place to the big cities of the industrial north. It is recognized academic theory that even with migration, enough people of a particular surname tend to stay in and around the same place, so that counties showing the highest occurrence of a name are more likely to prove fruitful in searching for ancestors of that name.