University of Tennessee political science professor Nathan Kelly co-authored a study entitled "The Rise of the Super-Rich: Power Resources, Taxes, Fincancial Markets and the Dynamics of the Top 1 Percent, 1949-2008" with Thomas W. Volscho of City University of New York--College of Staten Island, which was published in the American Sociological Review journal on Monday.
The researchers studied how much of the national income flowed to the top 1 percent of earners over those years, and found that when Republicans control congress, there is much greater income disparity among Americans.
The study shows that from 1949 up till 1980, the top 1 percent of earners pulled in about 10 percent of the entire nation's income. But when Republicans took over Congress in 1980, that changed. By 2007, the press release says, the study found the top 1 percent of earners had netted 23 percent of the nation's income. For every 1 percent increase of Republicans' share in Congress, the top 1 percent's share of income grew .8 percent.
"To a large extent, Congress sets the national agenda on taxes and legislation, and whether those policies favor corporations or individuals," Kelly said in the press release, to explain the correlation.
Corporate-friendly laws, the study found, boosts income inequality. Labor-friendly laws reduce it.
The study also found that when more people join labor unions, income inequality lowers. When fewer people join labor unions, the opposite happens. Lowering the capital gains tax and income tax increased income inequality. And when the S&P 500 stock index rose, so did income inequality. The same was said for the Case-Schiller home price index.