Source: Texas Transportation Institute. The Urban Mobility Study.
Due to congestion, most large American cities have experienced increasing delays since the 1980s. Traffic delays are commonly measured by comparing the actual/observed travel time (dominantly during commuting) with the theoretical travel time, which is the amount of time it would take if there were no delays. The difference equals the amount of time lost because of traffic delays. On average, motor commuters in large metropolitan areas in the United States lost 54 hours due to congestion in 2017, the equivalent of 6.5 workdays of 8 hours.
While traffic delays have been stabilizing in the majority of the largest cities between 2000 and 2008, the last decade has seen ongoing growth in the average delay per motor commuter. For instance, for Washington, this figure used to be 86 hours in 2008 and went down to 102 hours in 2017. This is in part due to a decline in economic conditions, particularly lower employment rates. Other factors are also at play such as the aging of the population and less suburban developments.