Final answer:
The extent of commercial zones beyond city limits varies and is dependent on local zoning laws and city planning; the exact mileage is not provided in the question.
Step-by-step explanation:
The student is asking about the extent to which the commercial zones for Springfield, St. Joseph, and Columbia reach beyond their city limits. Without specific numeric information provided within the context of the question, it's impossible to give an exact figure.
Commercial zones can vary greatly in size due to local zoning laws, economic development strategies, and geographical constraints. However, if this is a question from a specific textbook or course material, the answer should be given based on the facts provided therein. For real-world applications, one would typically consult city planning documents or municipal codes for each individual city.