The US has by far the best temperature record of any large area on Earth. We have an excellent network of 1200+ USHCN (United States Historical Climatology Network) stations with data going back to 1895 and earlier. The raw USHCN temperature record shows that there has been a slight cooling since 1920. USHCN is a subset of GHCND (Global Historical Climatology Network Daily.)
They claim that they adjust global temperatures to reduce overall global warming, but much of the fraud in the global temperature record is committed in their global station selection and homogenization, which has moved 15 degrees closer to the equator since the 1930’s.
This is the all of the US stations NOAA GHCND had available in 1920.
This is the tiny subset used by NOAA GSN GHCND in 1920.
The cherry picking of US GSN GHCND stations is a farcical tiny subset of what is available.
The average latitude of the US GSN GHCND stations has moved more than 1.5 degrees to the south.
The roots of this fraud goes back to at least 1999, when NASA’s James Hansen complained that the excellent US temperature record didn’t match the farcical global temperature record.
So NASA and NOAA took a two-pronged approach to US temperature fraud. For the global temperature record, they cherry picked a tiny, non-representative set of US GHCND stations. For the USHCN temperature record, they massively tamper with the data to produce fake warming.
Their data tampering precisely matches their CO2 warming theory. Science at its absolute worst.
The GHCN/USHCN methodology is all peer-reviewed, which shows how corrupt and incompetent the climate science community is.