For example, the only way I knew that I made it into the San Francisco Chronicle was that I have friends in that area that told me they saw it. You will find that you will get a lot more letters published than you know about. You also need to be aware that some papers only publish local letters. If a paper calls you and asks to be removed from your list, just do it. Don't let it discourage you.
Some papers also have a limit of one letter per month.
So even though they like what you wrote, if they already published a letter from you, it might not get in. You'd be surprised how few letters these papers get. I just got the above letter printed in the Kansas City Star. I talked to the person verifying my letter and asked her how many letters a day she gets. She said she gets about 30 a day, and they publish 8.