Town and county histories can be invaluable to form a picture of your ancestors in the time they lived in the area.
Always record females using their maiden names.
What happened to the 1890 U.S. Census? A fire broke out in the basement of the Commerce Building in Washington, D.C.on January 10, 1921. The census records were stored improperly in the basement and were soaked with water and no restoration efforts were made to save the documents. The damaged records were destroyed sometime between 1933 and 1935 when they were deemed no longer necessary.
In 1820 the Federal Government began requiring ship manifest lists but the early years can be difficult to locate.
Begin with the latest census available and work backwards. Census records have been taken since 1790. Before 1790 you can use Tax Lists and other local lists that might have been compiled according to the state you are researching in.