Drilldown: Collapsed Detail Lines Still Take Up White Space Instead Of Resizing On Page

I have a report that (for purposes of this example) displays States and the Cities in a state.



Now the State is the first group which I want to drill down into by expanding and then show the Cities as the detail line.



What I would expect to happen (and what does happen if I use the wizard instead of creating the report manually) is that I would click on a State and then the page would expand to make room for all the cities listed below.



(That is to say if I am showing only states, not expanded, then all 50 states fit on a single page. Then if I expand California all the states below that shift onto other pages to make room for the 400+ cities in California)



However, what happens is that when I preview the report instead of being 1 page long it is many pages in length with empty white space between the States (white space that would be occupied by the cities if I were to expand the state).



Can someone tell me what setting I need to adjust to get the report to dynamically resize when I expand/collapse groups?



Thank you.