number. More information and images of signage can be found here. On maps, business routes are typically denoted by a standard marker containing the route number and the abbreviation "BUS" (e.g., "BUS 81" inside a U.S. route shield to denote Business US 81). For Interstate business routes, an indication of whether the route is a business loop or business spur may also be included (e.g., adding "LOOP 44" inside the interstate marker). MDOT's official Michigan maps denote Interstate business routes with green shields that look similar to Interstate business route signage. Maintenance Business routes are maintained by different levels of government in different states. Many states incorporate business routes into their state-maintained highway systems; others, such as Indiana and Wisconsin, have entrusted business route maintenance to local governments. Formation Business routes typically follow the original routing of the numbered route through a city or town and were largely created during the era of large-scale highway construction in the U.S. from the 1930s through to the 1970s. As U.S. Highways and Interstates were built, they would typically begin in the first phase of their development with the numbered route carrying traffic directly through the center of a given city or town. In the second phase of their development, bypasses would be constructed around the central business districts of the towns they had once passed directly through. As these bypasses were built, the original sections of these routes that had once passed directly through a given city or town would often be designated as "business routes". In many cases before the construction of such bypasses, local businesses would attempt to exert legal and/or legislative pressure for these bypasses to be routed to maximize access between their businesses and the proposed bypass loops, while state planners might attempt to route such bypasses with less concern for the welfare of the businesses being bypassed. City routes City routes are most commonly found in the Midwestern United States, although there are a number of city routes in other parts of the U.S, as well. These routes serve the same purpose as business routes, but they feature "CITY" signs instead of "BUSINESS" signs above or below the route shields. The designations of many of these city routes are being phased out in favor of the business route designation. Another definition of a "city route" is similar to a county route, where a particular city forms its