U.S. population growth slowed over the last decade to its lowest rate since the Great Depression. The U.S. population is aging rapidly. While baby boomers have started to hit retirement age, challenging economic circumstances have caused many younger Americans to postpone having a family -- and this was before the pandemic made conditions even more difficult.

While the overall U.S. population still increased in the past decade, some parts of the country reported population decline, mostly due to people moving away. As people move away to either retire or to take on a new job, natural population increase (births minus deaths) has not been enough to offset net migration losses. Nearly every state has at least one county where the population declined significantly from 2010 to 2020 -- in some cases by well over 10%.

Economic opportunity -- or lack thereof -- can be a major factor that causes people to relocate. Most of the fastest shrinking counties in every state have an unemployment rate and a poverty rate greater than or equal to that of the state itself. Other factors, like prevalence of violent crime, lack of recreational activities, and other less desirable qualities can also be factors that cause residents to leave an area in droves.

The fastest shrinking county in New Hampshire is Coos County. The county's population declined by 5.7% from 2010 to 2020. The population of New Hampshire overall increased by 3.8% during that same time period, and the U.S. population increased by 6.7%.

Coos County's population declined by 1,878 people during the decade, from 33,052 in 2010 to 31,174 in 2020. It is one of just a handful of the fastest shrinking counties in a given state with a positive net migration as 35 more people moved to the county than moved away from it during that decade.

To determine the fastest shrinking county in every state, 24/7 Wall St. reviewed data on population from the U.S. Census Bureau's Population and Housing Unit Estimates Program. Counties were ranked based on the total population change from 2010 to 2020. Only counties with at least 10,000 residents in 2010 were considered. Data on population change due to natural growth and net migration also came from the Census Bureau PEP program. Data on median household income and poverty rate came from the Census Bureau's 2019 American Community Survey and are five-year estimates. Data on unemployment for May 2021 came from the Bureau of Labor Statistics and are not seasonally adjusted.


StateCountyTotal population, 2010Total population, 2020Total population change, 2010 to 2020
AlabamaPerry County10,5778,687-17.9%
AlaskaKodiak Island Borough13,60612,992-4.5%
ArizonaCochise County131,359127,450-3.0%
ArkansasPhillips County21,75517,299-20.5%
CaliforniaLassen County34,89530,016-14.0%
ColoradoLas Animas County15,50614,420-7.0%
ConnecticutLitchfield County189,876179,610-5.4%
DelawareNew Castle County538,496561,5314.3%
FloridaGulf County15,86313,534-14.7%
GeorgiaMacon County14,74312,712-13.8%
HawaiiHonolulu County953,203963,8261.1%
IdahoFremont County13,24313,218-0.2%
IllinoisCass County13,64111,925-12.6%
IndianaBlackford County12,76611,782-7.7%
IowaEmmet County10,3029,095-11.7%
KansasMontgomery County35,46831,502-11.2%
KentuckyLeslie County11,3109,637-14.8%
LouisianaMorehouse Parish27,97924,227-13.4%
MaineAroostook County71,87366,804-7.1%
MarylandAllegany County75,04270,057-6.6%
MassachusettsBerkshire County131,274124,571-5.1%
MichiganGogebic County16,42413,842-15.7%
MinnesotaKoochiching County13,31912,059-9.5%
MississippiCoahoma County26,15121,564-17.5%
MissouriDeKalb County12,88810,944-15.1%
MontanaFergus County11,59011,104-4.2%
NebraskaBox Butte County11,30810,696-5.4%
NevadaWhite Pine County10,0269,466-5.6%
New HampshireCoos County33,05231,174-5.7%
New JerseyCumberland County156,610147,008-6.1%
New MexicoColfax County13,75111,927-13.3%
New YorkDelaware County47,96243,938-8.4%
North CarolinaNorthampton County22,10419,088-13.6%
North DakotaWalsh County11,12610,437-6.2%
OhioMonroe County14,63113,586-7.1%
OklahomaBlaine County11,9439,447-20.9%
OregonMalheur County31,31630,983-1.1%
PennsylvaniaCambria County143,693128,672-10.5%
Rhode IslandBristol County49,84248,350-3.0%
South CarolinaAllendale County10,4198,331-20.0%
South DakotaYankton County22,43822,7421.4%
TennesseeHaywood County18,80517,002-9.6%
TexasHale County36,20732,754-9.5%
UtahEmery County10,97610,147-7.6%
VermontRutland County61,65957,764-6.3%
VirginiaBuchanan County24,10920,613-14.5%
WashingtonYakima County243,240251,8793.6%
West VirginiaMcDowell County22,10816,916-23.5%
WisconsinPrice County14,15913,245-6.5%
WyomingCarbon County15,88414,711-7.4%