Where do I find the lattitude and Longitude in the SASHELP tables that match to the CLAT and CLNG values used in your code. I used "x,y" and "LAT, LONG" and I'm not having any luck.

Your example:
datalines;
Washington, DC 38.917117 -77.041187

SASHELP.UScity

county_ state_
Obs STATECODE statename CITY cityname code X Y LONG LAT code

3242 DC DISTRICT OF COLUMBIA Washington WASHINGTON 001 0.25291 0.059187 77.0132 38.9136 11