The average length of a rural route is 55 miles.
( ( ( The ( average length ) ) ( of ( a ( rural route ) ) ) ) ( ( is ( 55 miles ) ) . ) )
(ROOT (S (NP (NP (DT The) (JJ average) (NN length)) (PP (IN of) (NP (DT a) (JJ rural) (NN route)))) (VP (VBZ is) (NP (CD 55) (NNS miles))) (. .)))
55 miles is the average for a rural route.
( ( 55 miles ) ( ( is ( ( the average ) ( for ( a ( rural route ) ) ) ) ) . ) )
(ROOT (S (NP (CD 55) (NNS miles)) (VP (VBZ is) (NP (NP (DT the) (NN average)) (PP (IN for) (NP (DT a) (JJ rural) (NN route))))) (. .)))