Is there a website that will list dividends annually for AT&T stock purchased in 1957?

Your best bet is AT&T itself. Their shareholder services division would have that information.

Remember that you're looking for history of AT&T Corp. not AT&T Inc. I found it here:

AT&T Corp. Dividends | Investor Relations | AT&T (http://www.att.com/gen/investor-relations?pid=9504)

It's confusing, but when SBC (nee Southwest Bell) bought AT&T Corp 1n 2005 they changed the name of the combined enterprise to AT&T Inc. So web sites that today show the history of "AT&T" stock are actually showing the history of SBC, which came into being upon divestiture from AT&T Corp in 1984.

Note the web site that I referenced provides both AT&T Inc and AT&T Corp dividend data.

May I ask why you need this data? If it's because you are trying to figure the cost basis of some AT&T stock you own (perhaps shares you bought pre-1984 through a Dividend Reinvestment Program), it's going to get very complicated trying to track cost basis through all the various stock splits, company spin-offs, and mergers that have occurred since the original AT&T divestiture in 1984. But there are some helpful web sites that I can point you to in order to help figure it out.