No different in any city. The prefex 2,3,4,5 etc. just means its a bypass route to eliminate traveling through the main part of a city. If your on 290 going around Chicago, eventually you will be back to 90. 90 is an east/west route across the country and the bypasses in every state it goes through will have a prefex to allow you to skip the city traffic. Check 75 to Florida, or 80 to California. Not really confusing if you keep it in mind. Even numbers East/West, Odd numbers North/South, just like they were before any expressways were built in the 50s. Route 31, route 64. same pattern.