1:2,000,000-scale Hydrologic Units of the United States (OLDER)
This data set has been superseded by huc2m. 
This file contains hydrologic unit boundaries and codes for the conterminous 
United States along with Alaska, Hawaii, Puerto Rico and the U.S. Virgin Islands. 
It was revised for inclusion in the National Atlas of the United States of America, 
and updated to match the …