READ ME:

As a partnership/contributed dataset, the data originally delivered to USGS was not necessarily edited to USGS Base Specification beforehand, 
and hence still had a variety of hydroflattening errors in the breaklines and DEMs.
Before publishing such datasets, the USGS completes necessary edits so the DEMs meet the USGS Base Specifications. 

There are 2 breaklines shapefiles provided here:

In the folder titled "Breaklines_NGTOC_Edited" are the final resolved breaklines used to produce the DEMs published on the National Map. 
 - The USGS recommends using this breakline dataset for any DEM exports or additional editing of the breaklines, 
   as all the simple hydroflattening errors have already been resolved.

In the folder titled "Breaklines_Original_Contractor" are the raw contractor delivered breaklines before any modifications were made. 
 - The USGS does not guarantee the quality or efficacy of this breakline dataset, but provides the file in case users may find them useful for any purpose.
 - Use this dataset with caution, as a variety of hydroflattening errors remain in these original breaklines.