The ancestral puebloans in the 4 corners region (where Utah, Colorado, New Mexico and Arizona meet) likewise used the sun as a calendaring tool.

http://www.solsticeproject.org/

Unfortunately the Sun Dagger site about 3/4 of the way up Fajada Butte is no longer accessible by the public. Still there are other notable celestial alignments discovered in Chaco Canyon including corner windows that frame a certain star or lunar or solar rising or setting point at a particular time of year. There's a corner window shown in my avatar from the Pueblo Bonito ruin, though I don't believe this particular window has any alignment data associated with it.

Calendaring becomes pretty important when you are engaged in subsistence agriculture for a large part of your diet.

Regards,

Jim