The graph below shows the almost two degree US upwards adjustment trend being applied by USHCN between the raw thermometer data and the published monthly data.
The adjustments they are making are greater than the claimed trend, meaning that all man made US warming is occurring inside ORNL and GISS computers.
There is no legitimate physical explanation would would explain such a regular trend in temperature bias – other than UHI, which has the opposite polarity.
In their literature, they document 0.5F worth of adjustments, not 1.8F . They are delivering data with more than 300% of the adjustments described in Menne et al.