Did the United States grow more unequal while Republicans were in power? It sounds crude, but Princeton political scientist Larry Bartels has gone a long way toward proving it. Bartels looked up income growth rates for families at various income percentiles for the years 1948 to 2005, then cross-checked these with whether the president was a Republican or a Democrat. He found two distinct and opposite trends. Under Democrats, the biggest income gains were for people in the bottom 20th income percentile (2.6 percent). The income gains grew progressively smaller further up the income scale (2.5 percent for the 40th and 60th percentiles, 2.4 percent for the 80th percentile, and so on). But under Republicans, the biggest income gains were for people in the 95th percentile (1.9 percent).
