3

If you go to the Census Bureau's website there is a web interface to download Primary, Secondary, and All Roads (FTP link doesn't appear to be working at the moment). The All Roads option is only available per county. Does a 2016 dataset or web service already exist, free or not, where all these county datasets have already been compiled together?

4

You can "extrapolate" the download links from the source code

See javascript function goDownload()

 function goDownload(directory, filename)
    {
      var URL="getFile.php?year=2016&directory="+directory+"&filename="+filename;

      document.getElementById('downloadFrame').src=URL;
    } // goDownload()

and similar functions goDownloadNational(), goDownloadState(), goDownloadCounty().

You can see also in the source code where these functions are called (about line 4130 in my version)

onClick="javascript:goDownload('PRIMARYROADS', 'tl_2016_us_primaryroads.zip')

So you take these two variables, directory and filename, and generate a complete URL with the values from the dropdown

"getFile.php?year=2016&directory="+directory+"&filename="+filename;

becomes then

https://www.census.gov/cgi-bin/geo/shapefiles/getFile.php?year=2016&directory=PRIMARYROADS&filename=tl_2016_us_primaryroads.zip

which works (26 MB).


You have to then write a small script that loops over all states and countries and then make a URL based on the formula in each function, and then make the queries 1 by 1 (maybe with a short pause, to not get your IP address blocked)

  • Once you have the list of URLs use "wget" or something similar – Grimaldi Sep 4 '17 at 11:06
  • yes - and then share the raw data for the community! – philshem Sep 4 '17 at 12:29

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