This post is more of an answer than a question. Hope that’s OK.
A few years ago I was surprised to discover that there was not a list of federal ArcGIS server addresses. So I started making such a list to help with my Leaflet mapping projects. Sure enough, that work expanded and the list now includes state, county and local ArcGIS server addresses.
Note that this list focuses on server addresses, not portals. Each address is scanned by my code once per week and any dead links are fixed or flagged. An updated list is usually posted each week.
Here is the ArcGIS server list as a pdf file:
https://mappingsupport.com/p/surf_gis/list-federal-state-county-city-GIS-servers.pdf
And here is a csv file that you can use to import the server addresses into other tools. A description of the fields in the csv file is on page 2 of the pdf file.
https://mappingsupport.com/p/surf_gis/list-federal-state-county-city-GIS-servers.csv
Another one of my *volunteer* projects that some might find useful is GISsurfer. This is a web map based on the Leaflet map API that lets the user (1) ‘surf’ GIS layers on any public-facing (i.e. no login needed) ArcGIS server and (2) produce maps to display ArcGIS layers.
GISsurfer website: https://gissurfer.com
