NASCAR driver Dale Earnhardt Jr. to retire at the end of the year

— -- NASCAR driver Dale Earnhardt Jr. will retire at the end of the year, according to Hendrick Motorsports, his racing team.

"After 18 seasons and more than 600 races behind the wheel, Dale Earnhardt Jr. will bring his NASCAR Cup Series driving career to a close at the conclusion of 2017,” a statement from the group says. “Today, he shared the news with members of his No. 88 Hendrick Motorsports team.”

The 42-year-old driver returned to competition after a concussion sidelined him from NASCAR's top series for half of the 2016 season, and he has become a vocal advocate of sports-related brain injuries, NASCAR's website notes.

Earnhardt is ranked 24th in the Monster Energy NASCAR Cup Series standings, according to NASCAR.