Median age, 2013. (Niraj Chokshi)

The three states with the oldest populations — as measured by median age — are in the northernmost tip of New England, according to new Census data.

The median age of Maine, Vermont and New Hampshire is more than 42, with Maine and New Hampshire among the five states that saw that number rise fastest between 2012 and 2013. Forty-three states grew older last year, according to the Census data. Nationally, the median age rose a tenth of a year to 37.6.

Here are a few takeaways and maps based off the Census data, which was released on Thursday. The median is often preferred over the mean, or average, because the latter can easily be skewed. A small outlier group can skew the mean, for example, but may not affect the median, which represents the exact middle value.

An energy boom is making some states younger

The energy boom in the Great Plains is attracting young men, making several states in that region younger and more male even as the nation gets older, the Census said. Lindsey Bever has more on that over at Morning Mix.

The median age fell in Alaska, Hawaii and the Great Plains states of Montana, North Dakota, Oklahoma, South Dakota, and Wyoming. The steepest decline was in North Dakota, where the age fell 0.6 years.

At the county level there was, naturally, more variation. More than 1 in eight saw declines, with the median age falling 1.6 years in  Williams, North Dakota. The county with the highest age was nearly three times older than that with the lowest. Sumter, Florida, had a median age of 65.5, while Madison, Idaho had a median age of 23.1.

The map below offers another way of looking at how the age of each state has changed from 2012 to 2013. (Note: Oklahoma and South Dakota show no change, but in reality both became younger, according to the Census. The Census data provided is rounded to the nearest tenth, obscuring that change.)

Median Age, 2012 to 2013 change. (Niraj Chokshi)

Women are older in every state

Gender gap, median age, 2013. (Niraj Chokshi)

In every single state, the median age for women was above that for men.

The state age gap was larger than 3.5 years in Hawaii and Rhode Island and was the smallest in Utah, where just one year separated men and women. (It was smaller still in Washington, D.C., where the gap was just 0.3 years.)

Men are in the minority in all but 10 states

Male Median Age, 2013. (Niraj Chokshi)

Men made up a majority of the population in just 10 states: Alaska (52.4 percent), North Dakota (51.1 percent), Wyoming (51.0 percent), Hawaii (50.5 percent), Nevada (50.4 percent), Utah (50.3 percent), Colorado (50.2 percent), South Dakota (50.2 percent), Montana (50.2 percent), and Idaho (50.1 percent).

Female Median Age, 2013. (Niraj Chokshi)