Urban areas are richer and more productive. Research shows that doubling the population and increasing urban density boosts productivity by about 15%. Roman cities were connected by the distance someone could walk in one hour. Self-driving cars, trucks and buses will be able to eliminate traffic jams and then have steadily increasing safe operating speeds. The German Autobon has safe operation with people allowed to drive at any speed they feel is safe. This ends up grouping drivers into 80 mph, 100 mph and 120 mph groups. Self-driving vehicles and having some dedicated roads and highways would enable rapid deployment of fast inter-region logistics. This would be deployed far faster than the decades China has used for high-speed rail connections between and in large cities.

The ways in which density is linked to productivity has been developed in a wide array of research projects. Six key impacts are discussed in this section:
* density allows a higher degree of specialization, increasing efficiency;
* reduced transport time and costs for products/goods/services from one stage to the next, or from producer to consumer, occurs in denser areas if the transport infrastructure is sufficient;
* increased density increases the prevalence of knowledge spillovers, increasing innovation
* density allows firms to have access to larger markets of suppliers (especially labor supply) and consumers, allowing competition to enhance the quality of inputs and outputs;
* efficiencies of scale are created in denser markets where suppliers are reaching more potential customers;
* reduced land take in denser areas allows more economic activity to take place on a fixed piece of land than less dense designs.