While the population in Tennessee's metropolitan counties is expected to continue to grow, many rural counties are expected to see decreases over the coming decades, according to new projections released by the University of Tennessee.

The study released Friday by UT's Boyd Center for Business and Economic Research estimate that by 2040, Tennessee's population is expected to grow to 7.84 million people, with expected growth of about 50,000 people per year, according to a news release. That trend is consistent to population growth observed from 2010 to 2016 but lower than the average annual increases of about 65,500, which occurred in the 2000s. The lower growth in those years was due to trends in births, deaths, and net migration.

"All in all, these emerging trends imply changes in the expected demographic profile of the state. In the future, there is expected to be fewer working age individuals per retiree and greater racial and ethnic diversity," said Matt Harris, the study's lead researcher. "Most of these patterns in Tennessee are reflective of national trends."

The study projects growth and declines for each Tennessee county by race, age, and sex for each year from 2016 to 2070. These projections are informed by several emerging trends in population over the last decade including changes in births, deaths and net migration, the release states.

Natural population growth — the combined effects of births and deaths — in the state has fallen sharply because of increased deaths and decreased births. In 2007, Tennessee's population grew by almost 30,000 because of births and deaths alone. In 2015, the natural change was only 15,000, with two-thirds of that decrease coming from increases in deaths rather than decreases in births.

The decrease in natural growth was not distributed evenly across the state, but was concentrated in nonurban counties.

Other highlights from the study that contribute to the projections include:

BIRTHS

There is evidence, consistent with delayed family formation, that birth rates fell from 2007 to 2015— sharply lower among women younger than 25 years of age, but slightly higher among women aged 35 to 44.

In 2007, there were 86,661 live births in Tennessee. In 2015, there were only 81,000 — a decrease of 5,000 births per year.

Birth rates have fallen from pre-recession levels. In 77 of 95 counties in Tennessee, there were fewer births in 2015 than in 2007, with an average decrease of 55 births per county per year.

DEATHS

From 2007 to 2015, deaths per year in Tennessee increased from 56,800 to 66,329.

In 86 of 95 counties in Tennessee, there were more deaths in 2015 than in 2007, with an average increase of 110 deaths per county per year.

NET MIGRATION