bopeepsheep said "It'll be easier to just send it once we get there."We actually drove within 300 metres of the address (as the crow flies) while going west on Beltway 8. (Twice, in fact — once on our way out of the airport and again on the way to Katy Mills.) But we didn't necessarily know this at the time; it was probably just after we got back from Katy when I looked it up.
We never got around to getting a stamp to post it in Houston, and to our surprise there didn't seem to be postal facilities of any kind at the airport where we had a couple of hours to kill before flying back home.
So it had a free ride back on the plane and now it's back to plan A.