WASHINGTON—The number of Americans claiming new unemployment benefits has never been so low for so long.

Initial jobless claims, a proxy for layoffs across the U.S., decreased by 9,000 to a seasonally adjusted 233,000 in the week ended April 7, the Labor Department said Thursday. This means claims have now held below 300,000 for 162 consecutive weeks, cementing the longest streak for weekly records dating back to 1967.

The current streak eclipsed the previous longest stretch that ended in April 1970. Taking into account the size of the labor force, claims today compared to the late 1960s and early 1970s are much lower. In March, about 14 initial jobless claims were filed for every 10,000 people in the labor force, Labor Department data show. This compares with 23 claims filed per 10,000 in spring of 1969.

This year, about twice as many people are in the labor force as in 1969.

The consistently low claims levels point to labor market health because they mean relatively few Americans are losing their jobs and applying for benefits to tide them over until they can find new employment.