The historical movement of people and goods has been heavily influenced by advances in transportation. The invention of the steam engine and the expansion of the railroads opened the western United States to mass migration in the 19th century. Supplied with goods carried on those railroads, cities grew in all parts of the country. Many of them soon found density to be a challenge, especially when trying to travel from one part of the city to another. To alleviate this problem, public transit systems were introduced at the turn of the 20th century, and they remain in heavy use today.

Only a few decades later, the mass production of the automobile democratized individual transportation and substantially improved the efficiency of local travel. Now, well into the 21st century, we are on the verge of yet another advance of similar magnitude, one with the potential to have broad implications for the path and shape of real estate demand.

Unlike the advances of old, this one