New answers tagged spatial-database
buffer exclude points within distance range based on error testing. Your probably not looking for a merge but an exclusion based on factors such as position, date accuracy, goodness of data sets. Then you can compare and contrast and compare cleaned data, do checking through research to establish baseline for goodness improvement, run secondary process ...
The US Census has several files of different resolutions of just the state boundaries, for free here - http://www.census.gov/geo/maps-data/data/cbf/cbf_state.html
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