Looking for suggestion for the Atlantic NE for a month long trip

Fixed, my bad I spent so much time out west it's still on my brain. They were amazing trips, I expected to see nothing but sand and cacti, but only ran into majestic mountains and incredible scenery.

If you can do it in October, I would suggest new England. There is nothing more beautiful than the leaves changing colors.

Portland Maine in Sept/Oct would be a great base.

Really nice little city, great food, lots to do, lots of Airbnbs, good base to go other places in New England (Bar Harbor, White Mountains, etc)

Maine along the coast is awesome and there’s some great NE towns , just depends on your interests.

Recently someone asked about a road trip from eastern VA to Niagara Falls.
Below is a link to that post. I posted about our road trip from NC to NF. There are some ideas in that post.
What state are you starting from?

TigerDroppings post about trip to NY

These are some other places to consider east of MO and north of KY.
Eastern shore of Maryland and Viginia - St. Michales, MD, Chincoteague, VA.
Annapolis
Cape May NJ.
NY - The finger lakes area, Lake Placid, Fort Ticonderoga, Cooperstown
MA - the Berkshires (counties in western MA - towns of Stockbridge, Lenox, Pittsfield, North Adams). The Norman Rockwell museum is in that area as well as Tangelwood. It's probably too early for a concert but you can tour the place.
KY -Bowling Green to see Mammoth Cave and Corvett Assembly plant.
Ohio - Hocking Hills State Park, Air Force Museum in Dayton, Joe Burrow Stadium in The Plains
MI - norther Michigan would be out of your way probably but there is Sleeping Bear Dunes and further north is Mackinaw Island. But you could go through Wisconsin and go across the UP to get to Mackinaw Isl. and then go south.
VA - western and central VA: Skyline Drive in the Nat. Park. T. Jefferson's home Monticello,

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Get the National Park Service app that looks like this. In addition to the NP it also has all the other properties managed by the NPS. You can search by state, type of property (Park, Monument, Battlefield, etc), activities, etc.