i have a 500.00 bond dated 1914 is it good!?

Question

state of south dakota peoples gas company 500.00 dated feb 1,1914 due feb 1,1929

Answer 1

Probably valued only as a historical document and not for the dollar value of the certificate. Some people collect them, like stamps - it's called scripophily.

Here's an organization of collectors: http://www.scripophily.org/

Here are websites that buys and sells or auction such things:
http://www.scripophily.com/
http://www.stockandbondauction.com/

Answer 2

If it is a U.S. bond it is still good, but interest was probably frozen after it matured.