While the app does not specifically stop you from doing this, the app is not really appropriate for downloading the map of a full state.
State size downloads at full resolution are much too big to fit on your storage card. They could be upwards of 50 gigabytes. There are reports of the app hanging in a download because the size is simply too large.
Too many people are trying to do so, and it is putting a big strain on the servers.
Please refrain from doing so.
Please plan your adventures and download maps for the actual places you will actually go, instead of downloading a few whole states "just in case". Planning an adventure can be part of the fun.
We realize that there are some valid reasons for wanting a whole state with good detail, but at the present time we are not the right app nor do we have the right kind of maps to do so.