Final answer:
The maximum speed limit outside an urban district for a bus in Illinois is 65 miles per hour, with some exceptions.
Step-by-step explanation:
The maximum speed limit outside an urban district for a bus in Illinois, unless otherwise specified under the Speed Restrictions chapter of the Illinois Vehicle Code, is 65 miles per hour upon any highway with at least 4 lanes of traffic. This applies to highways where the roadways for traffic moving in opposite directions are separated by a strip of ground that is not surfaced or suitable for vehicular traffic. However, the maximum speed limit for a bus on all highways, roads, or streets not under the jurisdiction of the Department or the Illinois State Toll Highway Authority is 55 miles per hour.