A Voyage Long and Strange by Tony Horwitz

This book takes the reader along on the author's trip through the United States, tracking early American history. In addition to being quite well-written and very amusing, it seems to offer a fairly cogent, general, early history of American exploration, carefully tracking aspects of history that aren't necessarily taught in American elementary schools. It's a little casual for a formal history book (though it has a robust bibliography) and it's by no means comprehensive (although it is upfront about what it includes and excludes and why)--but well worth the read.