  Using the Panel Study of Income Dynamics data on the period 1982-1992, this
paper investigates some mechanisms of the labor market in the United States.
This market is analyzed as a stable structure constituted of segments which
present contrasted characteristics under the usual distinction between primary
and secondary sectors. Using a neural network algorithm applied on quantitative
variables measured at the level of heads of household, a broad classification
in four classes of situations is constructed. It shows a clear hierarchy going
from situations of very precarious work or no work at all, to situations of
stable jobs with higher wages than the average. A Markov chain, constructed
with the trajectories between the different situations of these workers, shows
a very stable structure of this segmented labor market. Keywords: segmented
labor market, unemployment, trajectories, Kohonen algorithm, Markov chain.
