Our county has a grid system for addresses. I would like to add a grid to my map that shows that information. I know that our 0,0 coordinate for the grid would be 41.54978, -87.336475. On East-West streets 330' feet will equal 100. For North-South streets 660' feet will equal 100. I think I would have to create a custom geographic coordinate system with the above formula and use that when I create a new grid in my data frame properties. How would I go about doing that? I have tried using a fishnet and I haven't gotten any closer to a usable result.