I would like to add this as well - Everyone else on this thread has pretty much covered everything that is said in here.
I thought this would be interesting to bring this up - There is a research group at the Salk Institute working on to invent Sign Writing. Now it might be a little bit complicated to understand the sign writing after looking at this video but once you get the hang of it, you'll be able to understand it easier. Now, with the Sign Writing - They are only preserving the ASL for research purposes and hopefully, trying to get that concept in the educational system.
Here's the video of Sign Writing - Deaf Perspectives on SignWriting® Video 1: How Deaf Opinions Changed - Google Video
It is just a thought that maybe one day it possibly could have ASL in a written language but however I am aware that ASL is not a written language yet.
