Metrication in the United States traditional mile-based lengths. In the Olympics, athletes run 1500 meters, not 1600 meters. Running races in the U.S. are usually run in metric distances (e.g., the 100 metres dash or the 5K run), although the mile distance remains popular. But even 5 and 10 kilometer races most often have mile markers on the course, and no kilometer markers. Long-distance races are often measured in kilometers, although exceptions exist (generally 10 mile races). The marathon is referred to as a 26.219-mile race (the official marathon standard distance originally being in English units — 26 miles, 385 yards) rather than 42.195 km.
2012 Olympic Marathon Course along the Victoria Embankment with the regular London Marathon course, the Olympic event also started in The Mall whilst the London Marathon starts in Greenwich, and the event followed an otherwise different course. The logistical problems behind the design of the London Marathon course (35,000 runners of mixed ability) are very different from those behind the design of the London Olympic Marathon course (100 top-class runners) hence the difference in the routes. The course for the Paralympic Marathon also had four laps which were nearly identical to the 2012 Olympic Marathon course, but avoided certain cobbled areas notably Paternoster Square,