Unemployed workers might want to think twice about depending on the Internet alone for a job search. Such hunting could prolong your unemployment.

Since March 2001, the start of the current recession, the average unemployment period has grown to more than 15 weeks. That’s three weeks longer than it took job seekers to get a job during the previous downturn in 1990-91, according to an analysis of data from the Bureau of Labor Statistics, conducted by Challenger, Gray & Christmas Inc.

Too many people are dropping resumes at an estimated 4,000 to 5,000 online job sites, blanketing the land with resumes that will not generate a phone call for the job seeker, said John Challenger, the firm’s chief executive.

“It is a formula for long-drawn-out joblessness,” he said.

Challenger suggests job seekers look for names, addresses and phone numbers online, but not to entrust their resumes’ future there.