The average walking speed is about 3 miles per hour for a woman, about 3.5 miles per hour for a man. So, at a pace of 3 MPH, it would take 433 1/3 hours, at 3.5 MPH, it would take about 371 1/2 hours.
Assuming a normal walking rate of 2.5 - 3.5 miles per hour it will take between 371 to 520 hours. Please realize that this is a theoretical answer, very few people will be able to walk this distance at the same rate (fatigue, blisters, pains, etc......).
260 hours at five mph
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