The best part is that they have to know the alignment the telescopes within .5 mm of each other, across thousands of miles.
Distances between locations:
Atacama, Argentina - Mauna Kea, HI - 6544 mi - 10532 km
Atacama, Argentina - Bishop, CA - 5305 mi - 8358 km
Atacama, Argentina - Mt. Graham, Az - 4742 mi - 7632 km
Mauna Kea, HI - Mt. Graham, Az - 2936 mi - 4725 km
Mauna Kea, HI - Bishop, CA - 2531 mi - 4073 km
Mt. Graham, Az - Bishop, CA - 581 mi - 935 km