There is no such thing as "standard" voltage in the States - since very few things have ever been standardized here (it is just a different philosophy as compared to, say, European union).
"Widely used" would be a more proper term. Unlike 60Hz frequency which would be hard to change (all rotating things depend on it etc.)
One may encounter 460V, 220V and 208V 3-phase systems almost equally often in industrial facilities in USA... kind of whatever the old habits were. Generally speaking, though, the newer plants are usually wired for 460 - great savings in copper, after all.