U.S. employers posted the most open jobs in December in the nearly two decades that records have been kept, evidence that the job market is strong despite several challenges facing the economy. The Labor Department said Tuesday that job openings jumped 2.4 percent in December to 7.3 million. That is the most since records began in December 2000. It is also far greater than the number of unemployed, which stood at 6.3 million that month.

Businesses have shrugged off a variety of potential troubles for the economy in the past two months and kept on hiring. The 35-day partial government shutdown began Dec. 22, and growth in China, Europe and Japan has weakened, threatening U.S. exports. Still, employers added 304,000 jobs in January, the government said earlier this month, the most in nearly a year. The jump in openings in December suggests hiring will likely remain robust. Openings are typically filled within 1 to 2 months. The surge in available jobs indicates that businesses expect demand to remain healthy and that they will need more employees to meet it.

A "'Now hiring" sign is displayed on the front entrance of a Staples store in New York City. Drew Angerer | Getty Images