Found the top graph via Paul Krugman’s blog. It is from a paper by Larry Bartels, professor of politics and public affairs at Princeton University.
{Click on the image to take a closer look}

I found a second graph in the same paper, showing the income inequality year to year (the 80/20 ratio measures the income inequality by dividing the income earned by someone at the 80th percentile by someone at the 20th percentile). Additionally, Bartels has highlighted the years Democrats and Republicans held the White House. Like a number of graphs on my site, you can see the increase in income inequality since the early 70s.
{Click on the image to take a closer look}

Data in the graphs are calculated from the Historical Income Inequality Tables compiled by the U.S. Census Bureau.
Addendum
5/2/08 Fix my definition of 80/20 income ratio
[tags]income, United States, inequality, Bartels[/tags]
Tagged as:
Blog,
Distribution of Income,
Income - Growth,
IRS,
Line Graph,
United States,
US Census
by Catherine on April 20, 2008
in Other
InflationData.com has a lot of information about inflation as well as historical data for the US, including estimates for Confederate Inflation Rates (1861 – 1865)
Tagged as:
Inflation
by Catherine on April 17, 2008
in Uncategorized
From the New York Times

[tags]Happiness, United States, Income[/tags]
Tagged as:
Choropleth Map,
Distribution of Income,
GDP per Capita,
Income - Average, Median,
IRS,
Scatter plot,
United States,
World
This graph shows the different types of income of the “Top 400″ from 1992-2005. Number one source of income is Capital Gains, which accounts for more than 50% of their income in 2005.
The “Top 400″ are the 400 tax returns with the highest adjusted gross income reported to the IRS.
{Click on the image to take a closer look}

Data from the IRS via Wall Street Journal’s Tax Report
[tags]Tax Rates, United States, Income tax, IRS[/tags]
Tagged as:
Area Graph,
Blog,
Income - High,
Income - Types of,
IRS,
Tax Rates,
United States