September 16, 2019

Population Trends: Data on Youngest Kids and New Adults

In the United States, the number of kids under the age of 1 fell by nearly 46,000 children from 2017 to 2018. The age group’s population count — which dipped to 3.9 million kids in 2018 — has been on the decline since 2015.

State-level statistics for America’s youngest kids echo the national data: From 2017 to 2018, every state but one reported having fewer children under the age of 1. The lone exception — Idaho — gained only 40 kids under the age of 1 during this time frame, according to the U.S. Census Bureau’s population division.

The trend reverses — just slightly — for America’s newest adults. The number of 18-year-olds increased from 4.2 million in 2017 to 4.3 million in 2018, according to national data.

At the local level, five states — Connecticut, Hawaii, Maine, New Hampshire and Rhode Island — saw their total number of 18-year-olds decline from 2017 to 2018. This difference was greatest — yet still marginal — in Connecticut, which reported 217 fewer 18-year-olds in 2018.

The total number of children (ages birth through 17) in the United States surpassed the 70-million mark in 1996 before peaking at 74.1 million in 2009. As of 2018 — the most recent full year of data on record — America’s child population count had dipped just below 73.4 million.