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Gridlocked cities: traffic patterns revealed across 20 major U.S. cities

Published on September 28, 2018

Interactive maps show dramatic speed reductions during rush hour

  • Congestion in 19 of the 20 cities peaked at either 4-5 p.m. or 5-6 p.m., while traffic peaked at 8-9 a.m. in Baltimore
  • Speeds drop 40% in Boston at 4.-5 p.m. and 38% in New York City at 5-6 p.m.
  • Washington D.C. has the slowest traffic with average speeds ranging from 19 mph at 5-6 p.m. to a maximum of 33 mph at 4-5 a.m.

Toronto, ON - September 26, 2018 - Geotab, a global leader in IoT and connected transportation, today revealed a series of interactive maps showcasing traffic patterns across the United States. Depicting drastic speed reductions during peak rush hour times, the Gridlocked Cities maps also reveal stark differences in congestion patterns throughout the day in 20 major American cities.


The interactive map series from Geotab enables users to view traffic congestion via an hour-by-hour breakdown within each city, providing insight into peak and average speed as well as speed decreases, the total number of vehicles on the road and peak hours for congestion. The Gridlocked Cities maps were created using 7.7 million aggregated traffic data records collected over the course of a year by Geotab GO devices in vehicles across the United States.


“Most drivers know when and where they’re likely to get caught in traffic in their area, but these maps allow users to explore the true scale of congestion across America,” says Mike Branch, Geotab’s VP of Data and Analytics.


Geotab data found that congestion hit all but one of the 20 cities the hardest in the afternoon and early evening, peaking at either 4-5 p.m. or 5-6 p.m. Baltimore was the sole exception, with roads slowing most significantly during the morning rush hour at 8-9 a.m.


On the contrary, the data depicts that Boston road users suffered the most significant drop in speeds across all 20 cities. At the city’s most congested time of day (4-5 p.m.), speeds fell 40% (relative to each location’s most free-flowing hour) down to an average of 22 mph. Similarly, New York is the second most congested city as traffic speeds dropped 38% to 22 mph at 5-6 p.m.


Those on the roads in St. Louis faced the fewest problems in terms of sluggish traffic with a speed decrease of 16% to 41 mph at the city’s most congested hour (4-5 p.m.).


Additionally, Geotab’s data also reported that Washington D.C. is home to the slowest-moving traffic overall, with speeds ranging from 19 mph at 5-6 p.m. to a maximum of 33 mph at 4-5 a.m.


“Around half of all congestion is recurring and reflects an overburdened infrastructure and lack of capacity on the road,” added Branch. “In addition to this, environmental, mechanical and human factors also contribute to congestion.


“Providing insight into traffic patterns can help to empower not only drivers but cities committed to improving roadways and their communites.”


Explore the interactive Gridlocked Cities maps in full here:


Traffic data consists of 7.7 million aggregated traffic data records collected by Geotab GO devices from August 1, 2017 to July 31, 2018 then aggregated by 7-character Geohash (area approx. 150m square) for each hour of the day. The speed drop for a particular Geohash during a particular hour is calculated relative to the fastest-flowing hour for that Geohash. Dot size is based on the number of vehicles in that Geohash in that hour. The 20 cities shown are the most populous metropolitan areas in the US, according to the Census Bureau Population Estimates of 2016. City outlines were sourced from individual states’ open data sites, road outlines © OpenStreetMap contributors.

Media Contact

Nicole Riddle

Senior Specialist, Strategic Communications

About Geotab

Geotab, the global leader in connected vehicle and asset solutions, leverages advanced data analytics and AI to enhance fleet performance, safety, and sustainability while optimizing costs. Backed by a team of industry leading data scientists, engineers and AI experts, we serve over 50,000 customers across 160 countries, processing billions of data points hourly from more than 4 million vehicles. Data security and privacy are at the forefront of all we do—trusted by Fortune 500 organizations and some of the largest public sector fleets in the world, we meet top cybersecurity standards. Geotab’s open platform and diverse Geotab Marketplace offers hundreds of fleet-ready third-party solutions. Learn more at and follow us on LinkedIn or visit Geotab News and Views.

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