WASHINGTON — American consumers are the most confident they’ve been in nearly 17 years, more good news for an already healthy economy.

The Conference Board said Tuesday that its consumer confidence index hit 125.9 in October, up from a revised 120.6 in September and the highest reading since December 2000.

The business research group’s index measures consumers’ assessment of current conditions and their outlook for the next six months. Both rose in October.

A healthy job market contributed to the sunny mood. Unemployment is at a 16-year low 4.2 percent. More than 36 percent of survey respondents told the Conference Board that jobs were “plentiful” — highest share since mid-2001.

The overall index hit bottom at 25.3 in February 2009 at the depths of the Great Recession before rebounding as the U.S. economy recovered.

Economists monitor Americans’ confidence because consumer spending accounts for about 70 percent of U.S. economic output. The economy grew at a healthy 3 percent annual pace from July through September.

The October confidence readings “suggest the economy will continue expanding at a solid pace for the remainder of the year,” Conference Board economist Lynn Franco said.