Nixon Letter to Supporter 1969

I just purchased a letter sent from the Nixon White House to a constituent in 1969. It thanks the constituent for his support of a speech made by Nixon regarding Vietnam. I am not sure but believe that it may be a machine-signed letter. I bought it with the envelope from the White House with a postmark.

If this is a machine-signed letter and not original does it still have any value? If so, how much?