Southern California, the New Jersey Coast, and New York City are the highly populated areas which have experienced the most warming over land in the US.
Worldwide, the earth’s surface has experienced an average temperature increase of 1º C or 1.8º F since preindustrial times. However, the earth is 70% covered by water, which has heated less. So land has heated more.
The Washington Post has taken NOAA temperature data starting in 1895 to 2018 and calculated the mean temperature rise of the lower 48 states, and found it to also be 1.0º C. It has also analyzed the US by county, and made the following map. The colors run from -1.0º C (light blue) to +3.0º C (dark red), by units of 0.5ºC. That is from -1.8º F to 5.4º F by units of 0.9º F.
The highest temperature rises in highly populated areas are in Southern California, the New Jersey shore, and New York City and Long Island. The South has, on the other hand cooled somewhat, leading to the 1º C average.
I don’t know if I can republish their graphs for each county, but in general, they show a fitted straight line with large fluctuations around it, and the final net temperature rise. The highest temperature rise was 2.6º C or 4.7º F in Ventura County, California. The other populous Southern California counties with large increases are: Los Angeles County with 2.3º C or 4.1º F; Santa Barbara County with 2.3º C or 4.1º F; and Orange County with 2.1º C or 3.8º F.
We also have to cover the New York City area: starting with New York County covering Manhattan with 2.2º C or 4.0º F; and the same for Bronx County covering the Bronx; and Queens County covering Queens.
Suffolk County New York was 2.3º C or 4.1º F; Nassau County New York was 2.2º C or 4.0º F; and Richmond County New York was 2.1º C or 3.8º F.
A year and a half ago, on Jan. 21, 2018, I presented maps and graphs from NASA GISS, which showed that World warming over land since 1880 was 2.0º C, or 3.8º F. That also included land warming over the US which was rather flat but fluctuating until about 1980, after which it had a steep rise. The warming from 1880 was about 1.3º C, or 2.3º F over the US.