Raynolds's 1848 expedition to the summit of Pico de Orizaba in Mexico predated what is known as the Golden age of alpinism (1854-65), when many major mountain peaks in the Alps were first climbed. The effort to summit the mountain was one of the earliest deliberate attempts to climb a major mountain peak, and involved logistics, planning and use of rudimentary climbing equipment, making it one of the more serious mountaineering expeditions undertaken to that point in history. Though unable to penetrate into the heart of what later became Yellowstone National Park, the Raynolds Expedition produced maps that were used by subsequent explorers to the greater Yellowstone region. Raynolds also located suitable wagon routes in the Bighorn Basin and was able to help narrow down the most appropriate routes for a future transcontinental railroad. The Raynolds Expedition further determined that few if any rivers in the region would be suitable for steamboats due to numerous rapids and steep gradients. Several lighthouses whose construction was designed or supervised by Raynolds are still in use and several are listed on the National Register of Historic Places.