That last map was drawn in the year of Sputnik. Direct exploration by spacecraft was not far off, so NASA needed a new map. The job went to the US Army and Air Force, who both had large mapping agencies and were gearing up for Moon mapping. I will show the Air Force map. You can see it here:

https://www.lpi.usra.edu/resources/mars_maps/MEC-1/

Look at that - it has canals! So did the less aesthetically pleasing Army maps. It's a curious footnote of Mars mapping history. #maps#Mars