Why do some data appear only at certain scales?
Some themes under the “A” button have associated minimum or maximum scales. This means that the data layer will not be drawn if the user is too far zoomed in or out for the data to make sense or be readable. For example, USGS quads will not be drawn if you are zoomed out more than 1:25,000. Some choices under the “A” button bring up 2 themes. For example, choosing “Infrastructure/Roads” will bring up a major road theme and an all-roads theme. If you are zoomed out and viewing a lot of area, only the all-roads theme’s label will appear in the table of contents, and the symbols for the roads will not appear. Instead, the major roads theme’s symbols will appear. It does not make sense to see every road when you are looking at the entire state, because not every road will be visible, and ArcView will spend a lot of time drawing. If you are looking at a small area, the all-roads theme will be drawn.
