<p class="p1">A pair of workers halts haying in the Sand Hills to watch with concern and awe as rolling thunderheads fill the afternoon sky.</p> <p class="p1">These photos are from the new National Geographic book <a href="http://shop.nationalgeographic.com/ngs/browse/productDetail.jsp?productId=6200956&amp;code=NG25157" target="_blank"><i>Greatest Photographs of the American West: Capturing 125 Years of Majesty, Spirit, and Adventure</i></a>, available now.</p> <p class="p1"><a href="http://national-geographic.cafepress.com/art/9431437">Buy a print of this photo</a></p>