Finally, Rick himself is a symbol, and a pretty big one. No, Rick, that's not a crack about your weight. So sensitive.
Rick's an American, and pretty much the only one in the movie. He holds out for a long time, doing whatever he can not to get involved in the war, or to take sides. He only inserts himself at the last minute, when it begins to threaten his own personal interests, and is finally inspired enough to make waves.
Sound familiar? It should. America acted exactly the same way when it was considering becoming engaged in World War II. It wasn't until Japan bombed Pearl Harbor (which, in our story, could be Ilsa's safety suddenly being threatened) that we were compelled to join the fray.
As with the actions Rick took to win his own private battle, America's involvement went a long way to deciding the outcome of the war as a whole. So all in all, a pretty perfect parallel there.
If you're still not convinced, check out Rick's fashion sense. If that goofy looking bow tie doesn't scream "America," we don't know what does.