There are also many different kinds of MUPs. At my house I have over 100 miles of Rails to trails (MUPs) that are unpaved and vary from crushed limestone smooth enough for road bikes to gravel, trap rock, sand and mud. Parts are inhabited by all comers and other part will occasionally have bikers on them. To the north in Massechusetts, I sometimes ride a paved trail near Ahmerst College that has everything including rollerbladers. The same for the Shining Sea Trail in Falmouth/Woods Hole Mass and the Cape Cod Canal access roads.
They are all fun and each has a different challenge.
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