There's a very cool site on the internet: walkscore.com It ranks the country's 40 largest cities based on their walkability.
Unfortunately, since we're 52nd, St. Louis doesn't make the cut for comparison purposes. It's too bad too, because when you enter "St. Louis, MO", it scores downtown a 95 - "Walker's Paradise".
Many St. Louis neighborhoods rate very well. It's easy to compare yours. Just click on the site, enter your address, and a custom map is created built around your address, scoring your neighborhood's walkability.
Among the city's most walkable neighborhoods are Soulard, the Central West End, and South Grand. But check some others. You'll be surprised how well St. Louis neighborhoods score.