It is a family tradition when a girl turns nine to go on a trip just with Mom. This was begun with my oldest who got so into the Laura Ingalls Wilder books when she was nine that we took a sojourn out west to see all the places she lived. It was a wonderful trip and when we returned, everyone said, "well, what are you going to do with the other kids?" and of course the answer was "take them on a trip, when they turn nine". Thus traditions are born. My current nine year old loves: adventure, odd things, such as "world biggest yarn ball" or "largest metal chicken", and nature. I'm not looking to do a big city, but a smaller town or road trip between several small towns. Must be continental USA, we live in Pittsburgh, so east coast is more likely. Time frame: it has to be during spring break (mid april). So far I have been looking at the Sequoia National Park/Kings Canyon in CA, but I'm worried it will be too cold in April. I see it's still considered "winter" until May.
Other ideas for quirky places to visit where it will be warmish in April?
I'd love to hear about fun mother-daughter trips!

You are not supposed to tag something with a state just becuase you live there.

Try to get your hands on a copy of "The Colossus of Roads: Myth and Symbol along the American Highway". Author Karel Ann Marling is a professor at the U of Minnesota in the American Studies Department. It is about those quirky pieces of Americana ones sees along highways scattered around the Midwest. You could find other quirky things nearby perhaps the Mustard Museum in Wisconsin.
The tag at the bottom of your question( you put Pennsylvania) alerts other posters who may have knowledge of an area and thus you will only get replies from PA travelers.. Ask Fodor's editors to remove your PA tag. Once you know where you're going, put that or those destination(s) as your tag(s) for help with travel specifics.

Take a look on www.RoadsideAmerica.com for some quirky things to see.

Another good resource is the "Weird (State Name)" series of books. My daughter loves taking weird road trips and she has done it in Pennsylvania, West Virginia, Texas and from Virginia to Memphis. She used the "Weird" books and the RoadsideAmerica website to plan all these trips.

BTW, if you don't mind going beyond the East Coast, Texas would be a great location for a mid-April "weird" roadtrip. The weather will be great then and the unofficial motto of Austin isn't "Keep Austin Weird" for nothing!

Go to Utah. Hike Arches National Park. See Goblin Valley. Go Canyoneering with www.deserthighlights.com My daughter went canyoneering the first time when she was 10. Very safe.

A lot of the main features in Sequoia will still be closed, even until June. You are likely to be required to have chains on your car(maybe maybe not).