The current study is an original investigation of the U.S. mortality pattern from 2000 to 2017. Previous research has shown that the unusual post-2014 decline in life expectancy is related to the increase in death rates for ages 25-44, mostly due to rising prevalence in drug poisoning and suicide deaths. Our investigation reveals that such increase in younger-age mortality has had an impact not only on life expectancy (or mean age at death), but also, and to a larger extent, on lifespan variability (the dispersion around the mean age at death). Even though lifespan variability is a key component of mortality change, as well as a measure of human well-being, with social, economic, and psychological implications, it has received much less attention than life expectancy has.