I give you these links of a competitor of you
, a man called Matt Green, that already took a walk across the entire U.S. (from Rockaway, Queens to Rockaway, Oregon) and right now he is walking every single street of NYC, that’s like 8000 miles. He expects to accomplish this goal in two years.
Here is the link to the NY Times article with his story.
http://www.nytimes.com/2012/03/25/ny...1&pagewanted=1
And to his blog, where he traces his route, and post the photos he took.
http://imjustwalkin.com/