Asha Bangalore of Northern Trust estimates that the economy will need to add 140,000 jobs a month next year to keep unemployment flat (let alone bring it down). Next year, the number may be a slightly lower but still high 86,000.

Why?

Because the "civilian labor force" grows about 1.2% a year (slightly slower in recovery years). (See chart above.) As a result, we need an impressive number of new jobs each month just to stay even.

Here's Asha:

The average growth of the civilian labor force in the last twenty years (1989-2008) was 1.2% and

the median also works out to be 1.2%. During the business expansion of November 2001 -

December 2007, the labor force grew at an average pace of 1.1% (median =1.1%).

For a steady unemployment rate, the rate of increase in employment should match the rate of

growth of the labor force. Based on the average growth of the labor force in the last 20 years, it

appears that roughly 140,000 jobs have to be created each month in 2010 to meet the increase in

the labor force. We computed this number by using the level of employment in the household

survey for November 2009 (138.502 million) as the starting point and raised the reading by 1.2%

(growth of the labor force). [Monthly increase in employment = 138.502 * 1.012=140.164,

(140.164-138.502)/12 = 138,502 jobs per month].

The labor force of the nation has recorded gains during the entire post-war period, with the exception of 1951. Data from the first eleven months of 2009 suggest that the labor force most likely held steady in 2009. The labor force typically grows at a sluggish pace compared with the historical average in the first year of an economic recovery (see chart 1), which leads us to

consider a slightly lower growth rate for 2010. By implication, the prediction of the necessary

increase in employment to match the growth of the labor force will be smaller than our estimate

of approximately 140,000 per month. Considering a 0.75% increase in the growth of the labor

force (one standard deviation below the 1.2% growth rate) would roughly require 86,600 jobs per

month. The main result of this exercise is that employment has to increase roughly 86,600 each

month in order for the unemployment rate to hold steady in the near term and a decline in the

jobless rate would entail a much larger gain.