My ggrandparents were their names . Their eldest daughter, Mary, is my grandmother. They raised their children in Michigan. My family website at address provided has more info about that family. From these you can glean a list of people with your surname in your state, city, county or country.
Cold letters have a very low response rate.
Learn some more about this before sending a mass mailing. You'll want to do it right the first time. The following web site has some good suggestions about cold letters.