Hartford and Springfield, MA area
Outsiders call it Northern CT and Southeastern MA
Locals call it the Connecticut River Valley
You'll occasionally hear the "Connecticut River Valley" used to refer to the Lebanon, NH/White River Junction, VT area as well. The preferred term locally is "Upper Valley."
Keeping in mind that
"the Upper Valley" extends pretty much the entire length of the VT/NH border.
A few more:
- The
"Northeast Kingdom" of Vermont, where I live, is both a common name for the region and is actually codified in state law as encompassing Caledonia, Essex, and Orleans Counties.
- The
"Champlain Valley" in Vermont refers to the area between Lake Champlain and the spine of the Green Mountains, including Burlington. I do not know if the term is also used on the New York side of the lake, or how far it would extend there.
- Several local terms for the Hampton Roads, VA area.
"Tidewater" is an occasionally heard term. Going into more detail, there's
"the Peninsula" (Hampton, Newport News, and other locales north of the James River), and
"Southside", which is everything south of the James River (i.e. Norfolk, Virginia Beach, Chesapeake, Portsmouth, Suffolk).
- In Minnesota, both
"the 'Cities" and
"the Metro" refer to the Twin Cities metropolitan area. Everything else in Minnesota is
"Outstate".
- Also in Minnesota, there's
"the Arrowhead Region" generally covering St. Louis, Lake, and Cook Counties (effectively everything east of US 53).
"Bluff Country" refers to the bluffs in southeastern Minnesota, generally east and southeast of Rochester.
"The Iron Range" is a stretch of northeastern Minnesota best known for iron ore and taconite mining, generally running from Crosby to Grand Rapids to Ely and southeast to Lake Superior, but with a modern-day focus on the Hibbing/Virginia/Eveleth area.
- Lastly, in local/advertising/food industry folklore, the
"Valley of the Jolly Green Giant" primarily refers to the Minnesota River Valley in the vicinity of Le Sueur, MN.