There were over 2.1 million pay phones in the U.S. at their peak in 1999, but now the technology is mostly relegated to nostalgia. Few wall-mounted pay phones linger in strip malls, and the silver and blue phone booths are mostly gone from the busy streets they once dotted in many parts of the U.S. Pay phones have become so rare that the FCC stopped requiring audits of them in 2018. RELATED: 50 Beloved Retail Chains That No Longer Exist Spokeo used data from the Federal Communications Commission to explore the fall of pay phones across the United States. States are ranked by the percentage dec…