What you need:
[Mapbox Account:][1]
This is where we will host a historical map online.
[Carto Account][2]
This is where we will pull our historical map layer into from MapBox. In addition, we will add data to our historical map layer, such as points and polygons.
[Download a HOLCMap:][3]
Mapping Inequality. You can download already georeferenced maps from this site.
[ QGIS instructions:][4]
QGIS tutorial for georeferencing a map.
[1]: https://www.mapbox.com/
[2]: https://carto.com/
[3]: https://dsl.richmond.edu/panorama/redlining/#loc=9/34.0071/-118.1566&opacity=0.8&city=los-angeles-ca
[4]: http://www.qgistutorials.com/en/docs/georeferencing_basics.html