The Aug. 21 solar eclipse will bring total or partial darkness to much of the continental U.S. – and with it, a potential traffic nightmare for drivers across the country.

While solar eclipses are a regular event, occurring, on average, once every 18 months, most of them happen across oceans or sparsely populated areas. This year's event is the first total solar eclipse in the United States in 38 years. The next may not come for another seven years. Vox.com has published a handy tool to find out how much of an eclipse will be visible from your zip code.

The entire U.S. will see at least a partial eclipse, but the sought-after total eclipse will follow a sweeping, narrow path from coast to coast. The potential for gridlock is even higher along the narrow band of total eclipse, which is expected to bring in floods of tourists to the 14 states along the eclipse path from Oregon to South Carolina.

In places like Kentucky, state and local agencies are preparing for the influx of visitors, asking people who must drive to plan ahead for any trips on the days surrounding the stellar event and to expect delays.

“We anticipate that a majority of the visitors will filter into the eight-county region over the two or three days before the eclipse,” said Wade Clements, Kentucky Transportation Cabinet district 2 chief engineer. “Once the eclipse is over, we are expecting traffic issues akin to what Louisville faces before and after the Kentucky Derby or Thunder Over Louisville. We urge motorists to plan ahead before traveling to or through the region the day of the eclipse.” 

In Oregon, the state Department of Transportation is taking a proactive stance on the expected traffic. ODOT has already warned residents that the eclipse could trigger the largest traffic event in the state’s history.

The Oregon Motor Carrier Transportation Division is taking steps to ease the congestion by banning certain kinds of traffic and roadside activity, including blocking over-width loads in the state from Aug. 18-22, stopping construction and non-emergency maintenance on state highways, and warning truckers of the lack of available parking and hotel rooms. In other states like Colorado, similar bans on oversized vehicles have also been issued to prepare for visitor traffic.

Some trucking companies have announced plans to reduce business in the most affected areas, with some companies cutting service entirely, while others are trying to plan around it, according to a KATU report from Portland, Oregon.

Each state will have restrictions in place to address the traffic, so make sure to check with the transportation agencies in each of the 14 states in the eclipse’s direct path to prepare for the traffic crunch. The Federal Highway Administration has set up apage dedicated to the August solar eclipse with links to state agency websites, general safety tips, as well as information on the event. It’s all a lot of preparation for an event that will only last a few minutes.