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Find more Brennan relatives and grow your tree by exploring billions of historical records. Taken every decade since 1790, the U.S. Federal Census can tell you a lot about your family. For example, from 1930 to 1940 there were 1,733 less people named Brennan in the United States — and some of them are likely related to you.

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Create, build, and explore your family tree.

What if you had a window into the history of your family? With historical records, you do. From home life to career, records help bring your relatives' experiences into focus. There were 25,812 people named Brennan in the 1930 U.S. Census. In 1940, there were 7% less people named Brennan in the United States. What was life like for them?

Picture the past for your ancestors.

In 1940, 24,079 people named Brennan were living in the United States. In a snapshot:

  • For 12,400 females, Anna was the most common name
  • 979 were disabled
  • 22,922 rented out rooms to boarders
  • The typical household was 3 people

Learn where they came from and where they went.

As Brennan families continued to grow, they left more tracks on the map:

  • 38% were first-generation Americans
  • The most common mother tongue was Gaelic
  • 2,548 migrated within the United States from 1935 to 1940
  • Most fathers originated from New York