Orizaba (5 636 m / 18 491 ft)

One of the issues related to Pico de Orizaba (the highest volcano of North America) is the numbers of its published heights. Any data from 18400 feet to 18900 feet are claimed as a true. With the increasing of GPS reliability the numbers informal and at least one scientific surveys have been taken to determine the true height of the volcano. According to Stephen Brown, a professor at the University of Texas (USA, San Antonio) the real height of Orizaba is 18490,5 feet with maximum error of 50 feet.