I've read this sentence in a grammar book.
'Outskirts are the parts of a city or town that are furthest from the center.'
Should I say 'the furthest':?:
In AmE, when it comes to physical distance, we tend to use "farther" and "farthest". We tend to use "further" and "furthest" for metaphorical distance. I have never heard the use of "furtherest".