A continuing earnings gap based upon an examination of 505 occupations:
Evidence from Census 2000 About the Earnings by Detailed Occupation for Men and Women
Census 2000 Special Reports      issued may 2004
   URL: http://www.census.gov/prod/2004pubs/censr-15.pdf

A Wage Gap "Favoring" Women Working Part-time, 50-52 Weeks per Year,
  URL: http://www.census.gov/hhes/income/histinc/p41.html

Wage Gap Favoring Men for Full-time, Year-round Workers, '60-'99,
  URL: http://www.census.gov/hhes/income/histinc/p38a.html

Gender Wage Gaps Persist within Women & Men of the Same Race-Ethnicity,
  URL: http://www.census.gov/hhes/income/histinc/p40.html

Wage Gaps Persist where Working Women Form Strong Majorities.
The Bureau of Labor web site provides tables of median weekly earnings, as well as worker numbers, of full-time wage and salary workers by 200 detailed occupations and sex. The tables are available in either TEXT or PDF formats. These tables may be incorporated into Excel worksheets, sorted according to the relative percentages of women workers in the occupations. Weekly median earnings for women and men may than be compared in occuptions where women form strong majorities. For a choice of table formats, TEXT or PDF, click on either option at:

  URL (Bureau of Labor): http://www.bls.gov/bls/blswage.htm
  For direct access to the pdf file: cpsaat39.pdf, click on:
  URL (Bureau of Labor): http://www.bls.gov/cps/cpsaat39.pdf

The Gender Wage Gap: Debunking the Rationalizations
   by Hilary M. Lips
   
"The U.S. Census Bureau has made available statistics on women’s and men’s earnings for several decades. By examining this time series of data, it is possible to get a feel for the changes and trends in earnings. One thing revealed by a simple visual examination of the series since 1960 is how closely the shapes of the two lines parallel each other. The dips and bumps in women’s and men’s earnings seem to move in tandem. Clearly, similar economic and social forces are at work in influencing the rise and fall of earnings for both sexes. Men’s earnings do not stand still and wait for women’s to catch up."
"The series of data points from 1960 onward provides a basis for a forecast of the future, although such forecasts are always estimates rather than hard certainties. When we used forecasting analyses to project the earnings of women and men into the future, to the year 2010, we found no evidence on which we could base a prediction for a closing (or widening) wage gap."
   The preceding quotes are from the seciton on: Is the Wage Gap Closing?
An on-line publication for Women's Media.com - The Site for Working Women
   URL (for the article): http://www.womensmedia.com/new/Lips-Hilary-gender-wage-gap.shtml
   URL (for Women's Media.com): http://www.womensmedia.com/

The basic data for addressing questions of a long term trends in the wage gap is available from the U.S. Census Bureau through their Historical Income Tables - People. To view all such tables, click on:
   URL: http://www.census.gov/hhes/income/histinc/incperdet.html
For comparing earnings by gender for full-time, year-round workers 15 years of age and older 1960-2001,
   URL: http://www.census.gov/hhes/income/histinc/p38.html

For more detailed comparisons of income (or earnings) by gender for more recent years, the U.S. Census Bureau and the Bureau of Labor Statistics have produced a series of Detailed Income Tabulations based upon the Current Population Survey (CPS). These can be reached by clicking on Persons for a particular year (eg. 2004, 2003, 2002 etc) at the following Census Bureau link:
   URL: http://www.census.gov/hhes/income/dinctabs.html

Wage Gaps in Elementary & Secondary Education,
  URLs(Bureau of Labor Statistics): http://www.bls.gov/  Pdf Document: cpsaat39.pdf   The specific link for
  this pdf document is: http://www.bls.gov/cps/cpsaat39.pdf  Since this table provides usual median weekly
  earnings by gender for a number of occupations, it is necessary to look up the information relevant to
  elementary and secondary education teachers.
  URLs for the Digest of Education Statistics gender-related salary statistics may explored from their home
  page for this information at: http://nces.ed.gov/programs/digest/  More specifically, such information for
  2002 may be found in Table 76 at link: http://nces.ed.gov/programs/digest/d02/tables/dt076.asp  This table
  (Average salaries for full-time teachers in public and private elementary and secondary schools, by selected
   characteristics: 1999-2000) may be downloaded as an Excel or Pdf file.
  U. S. Department of Education, National Center for Education Statistics maintains a School and Staffing
  Survey home page at:  http://nces.ed.gov/surveys/sass/  For a less recent analysis of gender differences in
  on earnings gender see, Chapter 4 Salary Differences Related to Teacher Sex and Racial-Ethnic Background
  in "The Patterns of Teacher Compensation" (January 1996), at link:
  http://nces.ed.gov/pubs95/95829.pdf