For many people, commuting to work is an almost ubiquitous daily occurrence that most strive to keep to a reasonable length.  But is this a uniquely modern difficulty, or did workers in past eras have similar commuter struggles?  That question is the focus of a CityLab article, which opens by introducing what is known as the Marchetti Constant, an idea coined by the Italian physicist Cesare Marchetti, which basically describes that people have always been willing to commute for about a half-hour, one way, from their homes each day.  The average speed of our transportation technologies does more than anything to shape the physical structure of our cities.  This article, which includes several illustrative maps and images, offers you a quick overview of the history of transportation and urban development.  Check it out!