Book excerpt: New York could have had a practical and profitable subway in operation by the 1870s—financed entirely by the private sector—had franchise terms been as liberal as those in Great Britain. Although it would not have been as technologically sophisticated as the 1904 subway, it would have been superior to the elevated railways of the time. Moreover, permitting experimentation and entrepreneurship in New York City's transportation industry would ultimately have accelerated the development of subway technology. Regardless, given the political constraints, the DBOM public-private partnership model finalized in 1900 was extremely successful. The lines built under this model comprise half of today’s New York City Subway network. Fares were low, no government subsidies were required, and investors earned high returns (until the unprecedented inflation of World War I, which could have been resolved by allowing the franchisees to raise fares with inflation).