If Yellowstone goes. Large parts of several states in essence cease to exist. Buried under so much soot and ash. Air travel is all but non-existent. Emergency response is crippled.

Massive Earthquakes would shake the area immediately around Yellowstone

Food production would cease for an undefined period. The air over large portions of the country would be unsafe to breathe for months if not longer. Problems mount further if water tables are contaminated.

Risks of soil contamination are also present. Which poses risks to farmland long term.

The humanitarian crisis would be unprecedented in U.S History. And the death toll would be obscenely high in a nation that has rising rates of asthma and respiratory conditions.

A blanket of soot is the absolute least of the problems that could arise if Yellowstone blows its top.