Portland really may be the most walkable American city I’ve been in – the only competition that springs to mind is the French Quarter of New Orleans, but that is such a small area in comparison.
Portland’s short blocks (generally 200 feet in length) help. So does the fact that Portland is actually being designed and managed to specifically accommodate pedestrians. A green streetscape (much stormwater management starts with lush streetside plantings that capture and filter run-off) and an interesting architectural mix, combined with a traffic management philosophy that favors pedestrians first (followed by bikes, transit, and finally cars) make Portland a walker’s dream.
When one gets tired of walking or wants to avoid the rain, transit lines are plentiful, convenient, and easy to use.