A New York-based nonprofit research group says over 1 million fewer job advertisements have been posted online since November.

The Conference Board released its monthly Help-Wanted Online Data Series report this week. It shows online advertised vacancies declined 506,000 in January to about 3.35 million ads.

The group’s Help-Wanted Online Data Series measures the number of new online jobs and jobs reposted from the previous month on more than 1,200 major Internet job boards and smaller Web sites that serve niche markets.

Online job advertisements dropped 507,000 in December, resulting in a 23-percent decline and over 1 million fewer Internet help wanted ads in the last two months, acording to the report.

Michele Sarin, manager of database analysis for the Conference Board, says the two-month decline is the sharpest drop since the agency began tracking online help wanted data in 2005.

“I’m looking right now at all the data back to May 2005 and this is by far the largest (decline) and each of the two months is larger than all of the previous ones,” Sarin said.

Mississippi (5.04) was second only to Michigan in the largest monthly ad decline in January per unemployed person. Michigan (6.45) had over six unemployed people for every advertised online job vacancy while there are five unemployed people for every online help wanted ad in Mississippi.

Other states with significant drops included, Indiana (4.78), Kentucky (4.72), North Carolina (4.31), Georgia (4.24), and Florida (4.20).

Texas had the largest overall decline in online job ads with a drop of 36,300. Advertised vacancies dropped in all 50 states last month with only two, North Dakota and Wyoming, with fewer unemployed persons than advertised vacancies.

“The very sharp declines in advertised vacancies throughout the nation in the last two months are clearly making it increasingly hard for those who are unemployed to find new positions,” Conference Board senior economist Gad Levanon said in a news release.

“An expected increase in the unemployment numbers coming out at the end of this week, combined with this sharp January drop in labor demand, will widen the labor supply/demand gap.”

In December, the number of unemployed people searching for work exceeded the number of advertised vacancies by 7.3 million, Levanon said.

Job postings declined in several industries, including transportation and material moving, office and administrative support, legal, business and finance, and construction, according to the Conference Board’s data.

Last month, there were 348,500 online ad vacancies for management positions, a decline of 175,800 or 34 percent from January 2008, data shows, and office and administrative support job positions dropped 156,900 and were 36 percent below January 2008.