There is a big difference between Charter Townships and non charter townships, Charter Townships have fixed boundaries that make it difficult to annex. Non charter townships are more easily annexed by neighboring communities the rules to how annexation happens varies on where the township is located in relation to the city, the number of people that live in the annexed area, etc. The Non Charter townships is the reason Ann Arbor keeps expanding its size. But Communities like Westland cannot annex Canton. Charter Townships pay less tax to the system and basically get subsidized by the cities in the County when it come to things like Roads, Sewers, Etc.