The US’s Crown Castle has been a trailblazer for towercos looking to extend their business model into small cells. That has involved investing heavily in fiber to support backhaul for dense neutral host networks. The company has announced its fourth fiber-related acquisition in two years, paying $600m for privately held Wilcon. The acquisition, from Pamlico Capital and other holders, will add 1,900 route miles of dark fiber to Crown Castle’s arsenal for small cell backhaul, mainly around the California cities of San Diego and Los Angeles. It will bring the towerco’s dark fiber total to 28,000 route miles, once the deal closes, probably in the third quarter. During the first year after that close, Wilcon is expected to contribute about…