This is generally not hard to learn. However, you should also know as much as possible about the emigrant, including the state, county, or area where he or she likely lived and the port from which he or she probably departed. You can often find this information in biographical sources in the country of arrival. Immigration sources, such as passenger arrival lists, usually identify the port of departure. If you know the emigrant's state or region of residence or port of departure, see Court Records, Emigration and Immigration, History, and Population.
Some surnames are more common in certain areas than in others.
It may be possible to determine what region or specific area the surname is found in, especially if you are dealing with an uncommon surname. Because records exist at all levels of jurisdiction, the more closely you can determine where your ancestor came from, the more records you can search. If you cannot learn the state or region where the emigrant lived, determine the general region or area where the family came from or where the surname is most common. After that, you might find emigration indexes or other sources that cover specific regions or localities. Many sources, such as census records and vital records in the country of arrival, may give at least a province name.