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15 May 2013 Last updated at 01:02 BST
The first German settlers arrived in Texas over 150 years ago and successfully passed on their native language throughout the generations - until now.
German was the main language used in schools, churches and businesses around the hill country between Austin and San Antonio. But two world wars and the resulting drop in the standing of German meant that the fifth and sixth generation of immigrants did not pass it on to their children.
Still the biggest ancestry group in the US, according to Census data, a large majority of German-Americans never learned the language of their ancestors.
Hans Boas, a linguistic and German professor at the University of Texas, has made it his mission to record as many speakers of German in the Lone Star State as he can before the last generation of Texas Germans passes away.
Mr Boas has recorded 800 hours of interviews with over 400 German descendants in Texas and archived them at the Texas German Dialect Project. He says the dialect, created from various regional German origins and a mix of English, is one of a kind.
"We have found no two speakers that speak roughly alike," Mr Boas told the BBC at his office in Austin.
The BBC's Franz Strasser went to Weimar, New Braunfels and Austin to find the last speakers of this dialect.