Philadephia to Seattle three week road trip in May

[AZBuck]

As promised, here's a suggestion for a return route from Seattle that stays a bit farther north so there won't be much, repetition of roads or sites from the outbound leg. It's also a bit more straightforward as there simply aren't as many roads/options across the far northern Great Plains.

So, just follow I-90 from Seattle to Worthington MN and then use MN-60/US-169 to the Twin Cities area. I-94 would be shorter, but the Rapid City SD area has several "be sure and see" places and is worth a day or two to itself. From MSP, rather than head down through or around Chicago, I'm going to suggest that you head through both the UP and the 'mitten' of Michigan. Start by continuing on I-94 but then pick up WI-29 near Elk Mound WI and take that to Shawano where you'd use WI-55 to connect to WI-22 to US-41. At Marinette WI-35 provides a nice lake-shore drive (actually along Green Bay) up to US-2 at Escanaba and follow that all the way to the Straits of Mackinac and I-75 south. At Flint, take US-23/US-223/I-475 south to I-75 north(!) to get on I-90 east. Because I-90 is a limited-access toll road, there is no direct connection between I-475 and I-90 where they cross each other. Then just take I-90 to I-80 across northern Pennsylvania to near State College where a final 'back road' connection, I-99/PA-26/PA-144/US-322/US-22 will bring you down to the Harrisburg area and I-81/I-83 will put you back on the PA Tpk for the final run back to Philly.

Highlights of this route include:
Little Bighorn National Battlefield

In the Rapid City Area
Mount Rushmore
Crazy Horse Memorial
Devils Tower
Wind Cave
Jewel Cave
Badlands NP

Mitchell Corn Palace
Soo Locks (a bit of a detour)
Colonial Michilimackinac
Cuyahoga Valley National Park

AZBuck