Where are large scale contours for viewing and download as shown in US Topo?

Large scale contours from US Topo products are now included in an ArcGIS REST service endpoint or WMS for viewing at scales of 50K and larger. US Topo contours were initially made available for download as of February 2013 as staged data in Esri File Geodatabase (FGDB) 10.1 format and pre-packaged in 1x1 degree tiles. In February 2014, staged contours were made available in additional formats of FGDB 9.3.1 or Shapefile, besides FGDB 10.1.