You are in Kansas, and that means that you will mostly suffer from cedar-hawthorn (or cedar-quince) rust. Look for lots of thickened, scaly spots on the twigs that are dead or dying. That is a good clue.
You will usually see these spot proliferating with fungal growth sometime in the late spring, then the branches die off later.
Preventative fungicidal treatments done earlier in the spring can help. No long term solution available, but some varieties are more sensitive than others. Some years back I had a customer with a really neat variety of hawthorn, a very elegant landscape tree. They had fewer crossing branches, and grew naturally into globe shaped tree. No pruning needed.
They all got wiped out in one year because of cedar-quince rust. The less sensitive washington hawthorns in the area were not affected at all.