-The weather project employs the ISC license, a permissive free software license
-written by the Internet Systems Consortium and functionally equivalent to the
-2-clause BSD license. Initially used for the ISC's own software releases, it
-has since become the preferred license of many projects (OpenBSD, for example).
+The weather project employs the ISC license, a permissive free software
+license written by the Internet Systems Consortium and functionally
+equivalent to the 2-clause BSD license. Initially used for the ISC's own
+software releases, it has since become the preferred license of many
+other projects.
+
+The correlation data provided is augmented by manual research but built
+primarily by aggregating sources within the USA Public Domain (U.S.
+Census Bureau Gazetteer and publications of the National Oceanic and
+Atmospheric Administration's National Climatic Data Center and National
+Weather Service including its National Centers for Environmental
+Prediction and Office of Science and Technology/Systems Engineering
+Center Geographic Information Systems Map Group). Copies of the original
+external data sources have been provided with this software for
+reference, but are not covered by the copyright or permission notices
+which follow.