 Approaching a population center, it is common for the parent route to split between a business route and a bypass route and rejoin to form the parent on the other side.The American Association of State Highway and Transportation Officials (AASHTO) defines a business route for U.S. highways as 
...a route principally within the corporate limits of a city which provides the traveling public an opportunity to travel through that city, passing through the business part of the city; while the regular number is used to obviate passing through the congested part of the city.This "Business Route" connects with the regular numbered route at the opposite side of the city limits.