If you like this sort of thing then you'd enjoy the book, "Texas Then and Now" by Richard Reynolds. It's a collection of photos taken from the late 1800's and early 1900's and then retaken from the same vantage points recently. It sits on my coffee table and has received many favorable remarks.
http://texana.texascooking.com/books/texas_then_now.htmThere are a number of 'rephotography' books out. Ones on New Mexico and the west in general come to mind, as well as several devoted solely to urban change in a number of cities.
One challenge, especially in the outdoors, is determining the exact spot a photo was taken from and matching the lens focal length to reproduce the scene. It would make a good hobby and far more intriguing than geocaching since there are few clues.
One of the easiest scenes to visit, and one that does not even take a camera to note the differences, is apparent to anyone who has traveled US90 across the Pecos River since the construction of Amistad dam. The elimination of a free flowing Pecos at its confluence with the Rio Grande, as the Pecos essentially became a still pool at that point with resultant serious sedimentation has reduced a great river that was nearly as wide as the canyon to a trickle that is choked with tamarisk and other invasive vegetation on the huge mud flats.
The change at that point is one of the greatest you can find anywhere and has occurred in the span of a generation or so. It took quite a number of years for the silting process to become apparent, but it then progressed with remarkable speed.
Of course, once Amistad fills up with dirt as it is well on its way to doing, then the dam can be removed/breached as it will be a useless artifact and the downcutting can resume.
