"America's State Parks and State-Owned Historic Sites" top the list, after unprecedented deficits have brought about deep cuts and even closures across the nation.
From the NTHP's website: "This year nearly 30 states have experienced cuts to parks' and sites' budgets, and a recent survey estimates as many as 400 state parks could close. While providing some short-term budget relief, this approach will actually cost states far more in the long term. Before they can re-open, state-owned and -managed resources will require massive investments to undo the damage suffered from abandonment, neglect, and deferred maintenance."
Hinchcliffe Stadium in Paterson, New Jersey, one of only three remaining Negro League stadiums in the country, is also along the list.