Way back in 1977 a couple of researchers hypothesized that more left-handed architecture students would successfully complete their six-year long educational program. In fact, 21 percent of men who started the program were lefties, well above the population average of 10 percent. (Although there were women in the program, none were apparently left-handed. Left-handedness is much rarer in women than men.) The lefties indeed did graduate at a higher rate proportionately than righties, scoring better on design and other academic measures [source: Peterson and Lansky].
The jury's out on exactly why this is the case, but one of the more prevalent theories is that lefties excel at 3-D thinking and perception, which is obviously a pretty important part of the design and construction process.