City limits

The terms city limits and city boundary refer to the defined boundary or border of a city. The area within the city limits is sometimes called the city proper. The terms town limits/boundary and village limits/boundary mean the same as city limits/boundary, but apply to towns and villages. Similarly, the term corporate limits is a legal name that refers to the boundaries of municipal corporations. In some countries, the limits of a municipality may be expanded through annexation.

In the United States, such limits are usually formally described in a state, provincial, or territorial law (or an appropriate regulation) as being under the control of the municipal corporation or agency that constitutes the city government. It is customary to indicate city limits with the posting of signs on major freeways, highways, and arterial roads. Note that New England states have a unique concept of "towns", which are similar in size to the civil townships in other States, but empowered with the authority exercised by municipalities in other States.

Property within city limits is subject to city taxation and city regulation, and expects city services. Areas outside any city's limits are considered to be unincorporated, and in most U.S. states they are by default regulated and taxed by the county. In others, areas outside of city limits fall within another type of local government, such as the civil township (a division of a county). Cities and towns may have extraterritorial jurisdiction beyond their limits, typically for zoning purposes. The distance this extends varies based on the population or area of the city, or which "class" it is considered to be under state law.

...
Wikipedia