Article: Central Tucson is bicycle-friendly. To the east of the University of Arizona, Third Street is bike-only except for local traffic and passes by the historic homes of the Sam Hughes neighborhood. To the west, E. University Boulevard leads to the Fourth Avenue Shopping District. To the North, N. Mountain Avenue has a full bike-only lane for half of the 3.5 miles (5.6 km) to the Rillito River Park bike and walk multi-use path. To the south, N. Highland Avenue leads to the Barraza-Aviation Parkway bicycle path.

Now answer this question: How long does N Mountain Ave have a bike lane?
half of the 3.5 miles (5.6 km) to the Rillito River Park