What is the average or median annual income of a two-income family in
the United States?

"In 2003, the nationwide median income for such a couple was $72,866."

"Federal Income Taxes and the Cost of Living" by J. Scott Moody and
David K. Hoffman, Tax Foundation(November 2003)
http://www.taxfoundation.org/sr125.pdf

"Moody and Hoffman use this data and Census Bureau data on median
incomes for dual-income couples to calculate the specific income in
each surveyed jurisdiction that is necessary to purchase the national
median standard of living and the federal income tax liability on that
income."

"Federal Income Tax Burden Falls Ever Harder on Taxpayers in Areas
with High Cost of Living" Tax Foundation (November 13, 2003)
http://www.taxfoundation.org/costofliving.html

Sincerely,

Wonko