If you're looking for an exact distance to run, you've come to the right place! iRunMaps allows you to narrow down your search results by using the Filter on the Search page. BUT, did you know you can enter in an EXACT distance and it will also give you the results that way?
Simply go to the Search Page.
Enter in the exact mileage you want to run (IE: 4.2 mi), be sure to input mi after the number.
Your results will look something like this: