I have two shapefiles, one a set of rail links and the other a set of population points. I have been able to associate the population points belonging to each rail link in modelbuilder. My problem is that I can???t find a way in modelbuilder to sum the population associated with each point into a single value and assign it to the link record. The spatial join tool in modelbuilder doesn???t allow one to summarize attributes like it does when you right click on the shapefile and hit join based on another layer???s spatial location. Any suggestions on how to accomplish this?