Zig Zag by Ellen Wittlinger
The story takes place in Iowa. Robin wants her boyfriend to go to Iowa University so she can be close to him, but he's going somewhere thousands of miles away. She is going to go on a road trip in a zig zag pattern, so where she lives doesn't really matter because the book will soon shift to her being on the road. Her dad lives in Arizona and they are planning on meeting him. The story may change because she is traveling so the environments and the opportunities presented to her in the different locations may change. It is in modern time. I think that the time could probably stretch out 10 years in the past or so because not much of it was different back then, the story would be similar. It would be totally changed if it were in the early 1900's or so because they were just inventing cars, let alone going on road trips.