One of the best sites for looking up historical stock prices is Yahoo Finance http://finance.yahoo.com/. Just enter the stock’s ticker symbol in the box next to "get quotes" and hit go.

In the left hand column on the next page, click on historical prices and choose the date range. You will see both actual and split-adjusted prices. Yahoo Finance has prices going back to the 1970s, even earlier for some stocks.

If you need an older price, check with the company (or its successor). Many companies list historical prices on their Web sites, often under Investor Relations.

For more information on looking up old stock quotes, go to http://www.sls.lib.il.us/reference/por/features/99/stock.html.