http://www.arizonaracinghistory.com/cactusderbyintro.htm has a good bit of history about the "Cactus Derby", it was 511 miles,
Briefly, when the cars were still a marvel in the US, and people raced them because it was the most incredible thing to do, faster than a horse could run, or a passenger could ride a train, all sorts of unusual events were almost commonplace to test drivers and the new contraptions called Automobiles, and a lot of people went racing in any form possible. The Paris to Peking, the New York to Paris, the New York to San Fran, the Vanderbilt Cup, beach racing at Ormond, Daytona, Bonneville and the dry lakes of So Cal... but you may not have heard of the LA to Phoenix races through the desert.
The lack of roads, lack of pre-racing course preparation, and there not being any gas stations, service stations, parts stores, helpful bystanders, mechanics, or even towns to drive through made desert races incredibly difficult.
http://sdautomuseum.org/events/desert-racing-history-michael-anthony doesn't have any details though
So I'm going to try to make it to that speech, or q and a, and learn! I did find out that the first car to win was a White car, powered by a steam engine. At that time (1908?) White was such a great car that the President got one,http://justacarguy.blogspot.com/2007/06/presidential-limo-circa-1909.html and Buffalo Bill did too http://justacarguy.blogspot.com/2011/08/buffalo-bill-drove-white-steamer-in.html
the first 7 years of the Cactus Derby winners were driving the White steamer I mentioned, then a Buick, a Kissel Kar, something called National Baby Blue, a Franklin (aircooled was an advantage in the hot Southwest), a Locomobile, and in 1914 Barney Oldfield won in a Stutz
The race took about 30 hours, was on Nov 9th, and the desert on November has cold nights, and days in the 70's