This is one reason that I have concluded that the is no "genealogy" in Arizona because all those with people who came into the state very early, in the 1800s, are well aware of their ancestors and everyone else came from somewhere else.
These types of questions usually arise in conjunction with a concomitant assumption that an difficult-to-discover ancestor was born in one part of the country and is subsequently found in another area without any supporting documentation about the move or the reason for the move. One example, involved a husband who was supposedly born in New Orleans and married a woman from Connecticut in the mid-1800s. My question to the researcher was "how did this couple meet and get married?" This was especially true considering the U.S. Civil War was happening about the time the event was supposed to occur. Some brief research showed a marriage record stating that the husband was born in Connecticut, the same place as his wife. The researcher had merely picked up someone with a similar name.
Within the past week, I have been asked about people who had similar issues with movements from the North to the South, including one claim that a family moved from the Northeastern U.S. to Georgia in the 1800s. The problem is that exceptions do occur.
Statistics concerning population movements are readily available for very recent times. One interesting example is the Census Flows Mapper from the United States Census Bureau. Older, historical data on migrations have been compiled in many formats. One notable example is the New England Historic Genealogical Society's Great Migration Project. Quoting from the GreatMigrations.org website:
The Project aimed to summarize and document everything known about the individual immigrants who came to New England in its first years of settlement. Now, fifteen years later, a substantial body of work has been produced: The Great Migration Begins: Immigrants to New England, 1620–1633 (three volumes), The Great Migration: Immigrants to New England 1634–1635 (currently three volumes covering surnames A–H) and the Great Migration Newsletter (now in its twelfth year), which addresses broader themes and topics.There are also huge studies involving various ethnic groups or people from one country of national origin. Here are some the multi-volume works:
- Glazier, Ira A., and P. William Filby. Germans to America: Lists of Passengers Arriving at U.S. Ports. Wilmington, Del: Scholarly Resources, 1988.
- Glazier, Ira A., and P. William Filby. Italians to America: Lists of Passengers Arriving at U.S. Ports, 1880-1899. Wilmington, Del: Scholarly Resources, 1992.
- Glazier, Ira A., and Michael Tepper. The Famine Immigrants: Lists of Irish Immigrants Arriving at the Port of New York, 1846-1851. Baltimore: Genealogical Pub. Co, 1983.
- Glazier, Ira A. Migration from the Russian Empire: Lists of Passengers Arriving at U.S. Ports. Baltimore: Genealogical Pub. Co, 1995.
Here is a sample of some additional resources:
- America Immigration and Migration Patterns
- U.S. Immigration Trends
- Migration Patterns Reveal Much about US Population, Research Finds
- American Migration Patterns - contains dozens of links to other websites
People seldom moved in a random fashion. This is especially true the further you go back in history. When my Third Great-grandfather moved from Rhode Island into New York in the late 1700s, his movement was part of a larger settlement pattern. See Migration Patterns in New York State.
As you move into the past in your genealogical research, you should become more familiar with migration patterns. Whenever you seem to find people in your ancestry that moved in way that was counter to the general migration pattern, there needs to be more research done. You need to be very careful that the individual that seems to have moved in some surprising fashion is not really more than one individual.