As of February 8, 2016, three live official trademarks (live plants, timepieces, and kitchen cabinets) were found on USPTO.gov for the exact term
Gettysburg, of course, is the famous historical Civil War site in Pennsylvania. Any use pertaining to its geographical meaning is generally not trademarkable and may be used in connection with the actual city despite trademarks for other uses.
We believe that this term would be safe to use for most uses (excluding a the three uses as specified above).
However, it is always best to consult with a trademark lawyer or expert for how this domain may be used in commerce.
Gettysburg would be a great business name for a business specializing in a city directory or a store selling Gettysburg memorabilia and souvenirs.
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