These particular lines in this layer were selected from the US Census Bureau's TIGER/Line Shapefile "Primary Roads." This layer may have been modified from the original to be simplified for the tutorial. The data in this layer are not better than the original sources from which they were derived. It is the responsibility of the data user to use the data consistent within its limitations. See the original data's metadata at: https://catalog.data.gov/harvest/object/2e2a46a6-4444-43d8-b7fc-498ad6874e38/html