When I went out into the country to talk about "The Case for America," my book celebrating the nation’s 250th anniversary, it was an immersion experience. The capital of our country is in Washington, D.C., and that’s where I’ll be on July 4. But the heart of America lies across the nation — "from the mountains to the prairies to the oceans white with foam," in the great American outdoors.To experience our vast land is always inspiring. It puts t…