a missing patch no more

a few years ago aaron made me a promise. he promised me that he was going to make me "fall in love with utah". as part of his plan, we started going on trips to southern utah to go hiking in the national parks. we bought a new backpack & a patch from every park that we had visited. when we moved to washington two years ago we had one park that we had yet to visit. not knowing how long we would be in washington i thought we would never get the chance to get that patch. this weekend, we made it happen. do you know which patch is missing?