I just came across this wonderful website by Paul Horsted that couples classic photos of Yosemite's past with photos that he has recently took from the exact (or almost exact) same spots. Highly recommended for any Yosemite aficionado.
http://www.paulhorsted.com/YosemiteYesterdayToday/
(Note: the website also has similar photos from other U.S. national parks too.)
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