I can tell you that it first of all hinges upon the individual member of Congress. Some really do take the time to read incoming letters; some sign the response letters personally, thereby glancing over the incoming letters in the process; and some literally never see a piece of mail in their entire tenure.
Regardless of how involved the member is with the mail process, realize that your response is going to come from a staffer. The staffer will be knowledgeable about the issue, and may even have to talk to the member to make sure he/she is accurately representing the member’s views. But at the end of the day, it still comes from a staffer. More likely than not, your concerns can be matched up against a standard form letter response that was written years ago and perhaps updated for current use.
Realize also that each congressional office receives an absolutely overwhelming amount of mail. Even my member, about as low-key and inconsequential as a member of Congress can be, still received thousands of letters a week. A high profile member in a leadership position will get even more mail. Look at it this way: Each office receives mail at least three times a day. More if the volume calls for extra deliveries. As such, your letter is one small scrap in a mountain of paper.
So what can you do to make your views stand out?
WRITE AN INTELLIGENT, COGENT, ORIGINAL LETTER
Of that mountain of mail I referenced, here is its approximate breakdown:
Spam (50%):
you know those pre-printed postcards you find in your favorite issue magazines and are urged to mail in? We got more of those than you’d believe. After the first one is received, a stock response is written and everyone who sends in the same postcard gets the same response back. Granted, the amount of spam received gets logged as for or against the topic at hand, but don’t think your spam is getting personal attention.
Special interests (45%):
For every single bill anywhere in the legislative machine (and there’s an awfully lot of it), there’s a company, organization, or association that wants to let us know how they feel about it. For the most part, we don’t care. I mean, you pretty much know how the NRA feels about any given gun bill, and unless the company is based in our district, well, it’s hard to care about a company’s concerns from six states away.
Original letters from someone outside our district, spammed to every member of Congress (3%):
It all revolves around whether you’re a constituent. Yeah, I know it seems that since they are US reps/senators they should represent everyone in America. In truth, they care about only a very, very small slice of America – those that can vote for them. If you’re not a constituent, it’s almost a sure thing that your letter will be circular-filed. Every time we got an open letter from a non-constituent written to every member of congress, we simply trashed it. We didn’t even bother to forward it to the correct member’s office, as they surely got a copy of their own.
Original letter written by a crazy in our district (2%):
To this day, I cannot understand how someone can be sane enough to put pencil to paper and write out their thoughts, and figure out how to address, seal, and stamp and envelope – yet still be crazy enough to write about the things they wrote about. I kept a folder full of some of my favorites. From the lady who was abducted by aliens/CIA operatives (it never was really clear which) and had her hair replaced with microtransmitters, to the guy who was being attacked by iridescent bubbles launched from the fake moon every time he stepped outside, the world is full of crazies who insist on writing their member of Congress. Needless to say, we don’t write back. I mean, what would we say?
Original, cogent, well-written letter from a constituent who gets to the point with minimum of spelling/grammatical errors (>1%):
These are the rare finds in a congressional office. Even given the overwhelming amount of mail each member receives, write one of these and you will be sure to stand out. If your letter is original enough – i.e., touching on a subject not yet brought up before – a staffer will actually have to research the issue and write you back an original letter. Such research may even involve speaking with the member to make sure the views represented are the member’s actual ones. Write these kind of letter often enough, and your name will become recognized as the guy/girl who might well be the only sane, intelligent constituent among the district’s more than half million.