Scientists from Climate Central said the state experiencing the highest temperature increase was Rhode Island, followed by Massachusetts, New Jersey, Arizona and Maine, LiveScience.com reported.
Both natural climate variability and human activity creating greenhouse gases play roles in the findings, the researchers said.
They calculated averages of the daily high and low temperatures from the National Climatic Data Center's U.S. Historical Climatology Network of weather stations to determine how much the average daily temperatures changed each decade over the past 100 years.
The pace of warming increased dramatically starting in the 1970s with every state showing a rise in overall temperatures in the past 40 years, they said.
The increase in the rate of warming coincides with the time the effect of greenhouse gases began to overwhelm the other natural and human influences on climate at the global and continental scales, the scientists said.
There were regional trends to the increases, they said, with states in the Southwest, Northeast, Upper Midwest and Northern Rockies showing the fastest warming, while states in the Southeast and Midwest regions tended to warm much more slowly.