Notwithstanding any provisions of Sections 3-2-3, 3-2-5 and 3-57-9 N.M. Stat. Ann. to the contrary, the residents of a contiguous, undivided territory within a class A county may incorporate that territory into a new municipality with boundaries closer than five miles to or coterminous with the boundary of an existing municipality by following all other provisions of the law governing incorporation, if the territory proposed to be incorporated has a population, as shown by the last decennial census, of fifteen thousand or more.