Originally Posted by GUWonder

Interesting, learn a new thing everyday about airports in the US at least. [He did say (with bold added for purposes of demonstration): "The highest commercial service airport that I know of is Denver, which is comfortably below 5,500ft."]

Out of the airports above, I've flown into only three of those and only one of those commercially.

I've landed and taken off from higher airports -- for Asia, in India, China and Tajikistan; for South America, in Argentina, Chile and Peru.