so when trucks would drive their chips out to California, some of the seals would open up due to the pressure difference between the high altitude air and the air sealed inside the bag
This is backwards, isn't it? Less dense air from Colorado would shrink the bag in California.
I'm guessing he was saying that while the chips were in transport of the passes into California, the low pressure at the high altitudes combined with the higher pressure in the chip bags would cause the bags to break open. They'd be back at normal pressure at the destination however.
I also think he meant East of the Rockies as to where they were made, considering West of the Rockies is California.
I think it depends where in Colorado they started and where they went after. I walked and hitched my way cross country this year. I did not go through Colorado but went up and down in altitude quite a lot. I was up around 7000 feet at least three times in states I never thought of as all that mountainous. And Cali has mountains, some of them quite high.
This is backwards, isn't it? Less dense air from Colorado would shrink the bag in California.