Ted Hazen's website, a huge resource of mill information, at
www.angelfire.com/journal/pondlilymill/menu.html

Trotter's Gunpowder Mill in Nancy O'Malley's "McConnell Springs Historical Perspective" at www.mcconnellsprings.org/

The "Mill Neighborhood" at Old Sturbridge Village at
 www.osv.org

Great Lakes Chapter of SPOOM website:
https://spoomgreatlakes.weebly.com/

Vince DiNoto maintains this site of mill photographs organized by states. The photographs on this site were taken by Mr. DiNoto during his extensive travels on researching of Old Mills. The site is not a complete inventory of mills in any state. https://sites.google.com/site/historicalmills/

Vince DiNoto created a Story Map of 99 different mills which includes information about the mill and a topographic map of the mill location. Mr. DiNoto is the Director of the National Geospatial Center of Excellence. More regional story maps of mills and covered bridges are in the works as well as other online resources. http://bit.ly/1g49aUJ

A Story map about Water Powered Mills Created by Vince DiNoto. https://storymaps.arcgis.com/stories/f7d002f861064ef086c39f97c19d7dd2

Mills and Covered Bridge Map curated by Vince DiNoto.  https://kctcs.maps.arcgis.com/apps/StoryMapBasic/index.html?appid=a1782a4ba2d346f980a236f14683dc60