By Lawrence DiCara, Ian O'Banion and Katherine Soule ( February 6, 2018, 11:58 AM EST) -- The world is becoming increasingly urban, resulting in larger cities with greater population densities than ever before. As of 2014, nearly one in three Americans lived in the country's ten most populous metropolitan areas.[1] The influx of people to a city strains a city's infrastructure, transportation systems and public services. Across the world, supporting the increasingly urbanized areas with appropriate infrastructure, water and sewage services, transportation and green spaces will cost an estimated $1 trillion annually.[2] As urban land availability decreases, land value increases. Innovative developers and municipalities have begun to recognize and capture the value of "air rights," "excess density rights," or "unused development rights."[3]...