__ City, Rarefied Denver Has a Lofty Altitude
Puzzle 16 of Patterns in Nature Pack
Question is: __ City, Rarefied Denver Has a Lofty Altitude
and the answer is: MILEHIGH
Word Meaning:
MILE — The international mile: a unit of length precisely equal to 1.609344 kilometers established by treaty among Anglophone nations in 1959, divided into 5,280 feet or 1,760 yards.
Definitions from Wiktionary.