Since this is a living Toolbox, I will be adding US State content as I have time.
Eventually, each page will have History timelines, including what and when they were part of territories, when each became a state, when each state began recording vital records, when each state had censuses taken, a county map of each state and resource links specific to each state. Just click on the state in the “Research by State” menu for the state you are interested in. If the state you are researching is not listed, then I haven’t gotten to it yet, but the following links should be helpful. The Red Book is an awesome resource and the link below is a FREE online version.
RedBook: American State, County, an Town Sources. Digitized and found at Rootsweb Wiki:
https://wiki.rootsweb.com/wiki/index.php/Red_Book:_American_State,_County,_and_Town_Sources
Familysearch.org – United States Genealogy
https://www.familysearch.org/wiki/en/United_States_Genealogy
Ancestry.com U.S. State Research Guides
https://support.ancestry.com/s/article/State-Research-Guides-on-Ancestry-1460089695270-2866
Access Genealogy
https://www.accessgenealogy.com/america
US GenWeb Archives Special Projects – Broken down by state.
http://files.usgwarchives.net/
Ducksters Education Site
https://www.ducksters.com/geography/us_states/
Genealogyspot.com by state
http://www.genealogyspot.com/state/
The Library of Congress .. Researchers – Local History & Genealogy Reference Services
https://www.loc.gov/rr/genealogy/bib_guid/states/states_intro.html
Genealogy Trails – Scroll down to find a dropdown box to select the state
http://www.genealogytrails.com/#state
Random Acts of Genealogical Kindness (RAOGK) – Click on State Guides drop down box.
https://www.raogk.org/#
RESEARCH BY CATEGORY
RESEARCH BY STATE
RESEARCH BY COUNTRY