Cecil Adams wrote "Whatever Happened to the Canals of Mars?", as a response to the popular myth. Adams believes the lines spotted on the planet were an optical illusion. In 1877, Giovanni Schiaparelli, an Italian astronomer, was first to widely circulate observations of "canali" which means channels in Italian. The English translation of Schiaparelli's work became canals, implying a source of higher intelligence however. "This idea was taken up a few years later by the amateur American astronomer Percival Lowell, who had built an observatory near Flagstaff, Arizona. Lowell made detailed observations of Mars and published several popular books about the planet, notably Mars and Its Canals (1903), which included elaborate maps of the canals and outlined the theory that they were waterways used for irrigation."
Lowell is the principal source for the longevity of the myth with Lowell's 1909 map of Mars. Adams concludes the Mariner 9 satellite, which took close up pictures of Mars in 1971, dispelled once and for all "the canals myth" as an illusion, but at the same time, refers to many channels formed by some liquid that appear to be of natural origin. Adams, an obvious debunker, brutally concludes his response with throwaway lines, "...the old theory that one of the Martian moons is an artificial satellite is out the window, too. As for that business in recent years about a "face" on Mars … please, let's say no more."
Pictures taken by telescope of Mars such as this one by the Air Force as recent as 1962 along with a mapping history of the Red Planet can be found at the Planetary Blog. The pictures would seem to push the idea of canals at least into the sixties as the present writer remembers? Were the Mariner program pictures air brushed (no Photoshop) and why only map projections shown in this blog, which distort the planet's surface? The blog states the inelegant map projection is great for storing data but makes features far less apparent! Is the Red Planet really red or a tint added? Do you trust NASA? Please move along there is nothing to see here!