In the sweltering summer of 1801, as the Federal City was still finding its footing amid marshes and half-built monuments, President Thomas Jefferson - ever the Enlightenment figure with a farmer's appreciation for fine horseflesh - allegedly presided over or at least lent his prestige to a horse race in the fledgling Washington. The anecdote, dusted off and polished for contemporary telling, paints a scene of gentlemen in waistcoats and tricorn hats gathered near the President's House, wagering on blooded steeds pounding turf that would one day become Pennsylvania Avenue.