There are communities that have a Young Israel or Habad or other Orthodox shul that have certainly gone through the extent of building a shul building but not a mikvah (contra the halakha that a mikvah takes precedence). There are places in NJ and also Long Island that have a shul and even an eruv but no mikvah, but a person could drive to a mikvah within a reasonable distance, as Yehuda Yona stated.
