Distributed Transit Network
Automobiles use about 50% of oil. The only way to decrease the consumption of oil is to decrease the use of automobiles, and the only way to decrease the use of automobiles is to make denser cities and towns that can use electrified transit -- subways, light rail, and buses. Transit is completely dependent on density in order to thrive. There are many parts of the country that could have more transit now, even with their levels of density. But to make transit practical for most of the population, most of the population will have to live in dense areas.
The calculations here assume that transit would be free for riders.
Transit is a good example of how the expansion of one industry can help expand an entire industrial "ecosystem" of suppliers, as Jonathan M. Feldman points out.
To understand the employment generated by an expanded transit network, let’s look at the greater New York City metropolitan area. The Metropolitan Transit Authority serves about 15 million people, with 65,000 employees and a yearly operating budget of $13 billion. They have spent about $3 billion per year over the past 20 years on capital improvements, that is, manufactured goods like new subway cars and improved and new stations.
If about 5% of the country now lives in transit-friendly locations, and another 25% is added after twenty years, then for about 30% of U.S. population (about 100 million) to be able to use a system such as New York City’s, then the country would need about 7 such systems of 15 million people each, or about 1/2 million people employed to operate transit in the U.S, with a yearly cost of about 90 billion dollars.