Summary statistics for zipdistance25miles2009 dataset :

by Jean Roth , jroth@nber.org , 4 Jan 2016

    Variable |        Obs        Mean    Std. Dev.       Min        Max
-------------+---------------------------------------------------------
        zip1 |          0
        zip2 |          0
   mi_to_zip |  3,764,538    14.58841    6.712389          0         25

by Jean Roth , jroth@nber.org , 4 Jan 2016