US county-to-county and/or state-to-state migration flows - historic data for the 20th century

Question

I am looking for US county-to-county migration out flow data. That is, for every county in the United States (say, 1001 Autanga), the data would contain the absolute or relative number of people who migrated to other counties (say, 1002, 1003, ...) in that period.

I was able to find such data for the period from 1995 to 2000 (see here) as well as for the periods between 2000 and 2014 (see here) through the U.S. Census Bureau. Now I am looking for similar data for earlier periods throughout the 20th century. Say, for example for the periods 1920-25, 1950-55, 1970-75.

Any suggestions are much appreciated.

In absence of county data, I would also appreciate state-to-state migration for the same period.

Answer 1

There is a Forbes article with an interactive graphic for county-to-country migration based on IRS tax records. Each county-to-county move must have at least 10 people, so as to protect privacy. The available years won't go back as far you ask.

Article

Visualization permalink

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The link given as a source is available from the Internet Archive.

But the current IRS data is here. Available (tax) years are 1990-2015

You can download indidividual tax-years as a zip folder. Each zip contains Inflow and Outflow

Each Inflow or Outflow contains individual state files

Each state file contains then each county, inbound or outbound.

From the documentation (DOC):

For State-level tables, if fewer than three returns contribute to a cell, then that cell is suppressed and the information is combined with another cell in the table. Often, to fully protect the data, complimentary cell suppressions are also implemented. Similar procedures are used to protect cells with less than 10 observations in the county data tables.

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In addition to county data, state-to-state data is available with a similar process on the same page: