Crown Castle owns and leases roughly 40,000 cell towers in the United States. It also owns more than 90,000 route miles of fiber. It leases space on its towers to wireless service providers, which install equipment on the towers to support their wireless networks. Crown Castle’s towers and fiber are predominantly in the largest US cities. The company has a very concentrated customer base, with about 75% of its revenue from the Big Three US mobile carriers. Crown Castle operates as a real estate investment trust. It has announced plans to divest its fiber business, which should be finalized in 2026. After that, Crown will be a stand-alone tower operator.