Until a few years ago, the middle digit of North American area codes had to be a 0 or 1 (it's how the area code was identified when dialed), so putting them further away would result in fewer mis-dialed numbers that would inadvertently request a long-distance line.
Until a few years ago, the middle digit of North American area codes had to be a 0 or 1 (it's how the area code was identified when dialed), so putting them further away would result in fewer mis-dialed numbers that would inadvertently request a long-distance line.