Thermometers show a 60 year cycle US summer cooling and heating. Ten years of sharp cooling, followed by 50 years of gradual warming. The graph below shows two sharp cooling periods from 1895 to 1905, and again from 1950 to 1960. It also shows two warming periods from 1910 to 1950, and from 1960 to 2010.

The net temperature change over the period is zero. There has been no warming or cooling during US summers since the start of records in the 1890s. The 1930’s were by far the hottest decade.
But NOAA isn’t interested in the actual temperature record. Their purpose is convince people the planet is warming. So they “adjust” the temperature data (red line below) to create the appearance of a non-existent warming.

In doing so, they lose all of the useful information about US climate. The incredibly hot Dust Bowl becomes cooler than the cool present, and the only thing people are supposed to notice is that summers are getting hotter.
They accomplish this through a spectacular hockey stick of data tampering – shown below.

But it is much worse than it seems. Daily average temperatures are strongly affected by UHI. If we look only at maximum temperatures, it becomes obvious that US summers are on a long term cooling trend, and are currently among the coolest on record.

Here in Maryland, it probably is the coolest on record. We did not have a summer this year. A late spring, which has transitioned directly to autumn.
The NCDC adjustments destroy all meaning of the temperature record, and are used to produce political documents, not scientific ones.