I understood that all airspace in the USA above 1250ft was class E therefore controlled for IFR. Have I misinterpreted that?
In the lower 48 states, Class E exists above 1200 or 700 AGL for 99% of the country, but there are still some areas where class G extends up to 10,000' and higher. South and Southeast of Reno/Tahoe are examples. Others further north as well.