Any Input Appreciated

Sadly I only have a few covers in my collection and don't know a lot about them. I bought this one at the Mt. Rushmore visitors center some years ago and am now unable to find any information about it. Is it common to have a cover with two separate issues? Was this only created for sale at Mt. Rushmore, or was it standard issue? What is its value?

the stamps are SC#2523 (March 29) and 2523A (July 4). My 2012 Scotts specialized lists the FDC with single imprints for each stamp at $1.25 each. I don't know if there's a premium for having both on a single cover. Probably they had some of the March covers left over when the July issue came out. Modern first day covers don't really hold much value but maybe yours is a little better than most.
Not time to retire, anyway.

1970, Me 3-4 years old-
Cool place-
good luck

Its value to you is priceless as it has memories of your visit to Mt. Rushmore. The value to sell it on ebay or such is maybe 25 cents to 50 cents and not worth the cost to sell it. The value to a dealer would be less than zero since every item them buy has to make a good profit to cover their costs and pay their salaries so they can make a living for themselves and their families.

Thanks to all for your input. I have started the process of cataloging my collection and sought to fill in the value block but certainly agree that whatever goes in the value column, it is definitely priceless to me. Thanks again.

I would move this from my "stamp collection" to a page in my "family memories" album, and write a short note about the events from that trip, and mount both the cover and photograph on that page.