The state of Illinois currently has a Basic Speed Law on the books.
The Basic Speed law forbids drivers from going any faster than is
reasonable and proper based on road conditions like traffic and
weather. However, one person's perception of "reasonable and
proper" can vary significantly from someone else’s. For all of you
speed demons out there, the state has also set maximum speed limits for
different types of roads. Below are the statutory maximum speed
- In an urban district: 30 miles per hour on a regular road, and 15
miles in an alleyway.
- Outside an urban district: 65 miles per hour on all highways that
are operated by the Illinois toll authority and divided highways with 4
lanes or more. For all other highways, roads and streets outside of an
urban district: 55 miles per hour.
- Highways: 4-line divided highways have a speed limit of 65 miles
per hour by default. Other highways are 60 miles per hour.
- Trucks and buses have lower speed limits on highways than cars
While it can be helpful to know what the default speed limits are,
you should also be aware that the state of Illinois and local
municipalities can lower the speed limits if engineering and traffic
studies indicate that it would be a good idea to do so. Therefore, you
should always keep a lookout for speed limit signs to make sure that
you truly are going the speed limit.