Numerous clustering algorithms have been proposed that can support routing in mobile ad hoc networks (MANETs). However, there is very little formal analysis that considers the communication overhead incurred by these procedures. Further, there is no published investigation of the overhead associated with the recursive application of clustering algorithms to support hierarchical routing. This paper provides a theoretical upper bound on the communication overhead incurred by a particular clustering algorithm for hierarchical routing in MANETs. It is demonstrated that, given reasonable assumptions, the average clustering overhead generated per node per second is only polylogarithmic in the node count. To derive this result, novel techniques to assess cluster maintenance overhead are employed.