I'm trying to create a map book using Cartography - Data Driven Pages - Grid Index features. I want my Grid Index features to match or sit right on top of my own Map Grid. I have used many different processes and only one has come close. With a 1 inch away from the target layer all away around the Map Grid which is a polygon. Using the Page Unit and Scale option making the map scale 1:2519, Polygon width 15 and Polygon height 9, doing this the Number of Row = 24, Number of height = 35. I have even left these settings empty and still no luck. My input features is my Map Grid, but maybe I'm using the wrong target layer not sure...I even went into the environments to change my Processing Extent so that it matches my Map Grid. My page layout is 11x17, coordinate = Georgia 95. I do not understand what I'm doing wrong to get the final outcome; most of my layers include distribution facilities. Can some please help or give some kind of suggestions to get me on the right track, thank you in advance.