The American Dream is a very rocky little thing. When you wash up on its shores, the rocks will be the first things to hit your head. It's rough, difficult, and can hurt you. It's only when you tend to the wounds the rocks have given you that you're able to fully appreciate the beach you've landed on.
Lighthouses are usually very isolated. They're useless now, but they were handy back then. Nowadays, they've become something of a tourist trap. They attract all those curious, all those eager, and all those fascinated. Lighthouses, in that sense, are similar to America and the dreams all of its inhabitants have. The dreams have become easier since the end end of the Great Depression, but within those old roots is an air of intrigue and familiarity.
Roads are usually meant to lead you somewhere; the entire point of them is to safely take you from point a to point b. What if they never had an endpoint? If they did, you'd first think otherwise. As the road went on, you'd notice it. The thing is, a road can technically never end. It has to end somewhere, but it can certainly lead you nowhere. The American Dream is supposed to lead you somewhere. Like the uncertainty you'll face on a road that seems endless, you will always be uncertain if you are who you are supposed to be.