Households became more geographically segregated by income in the United States between 1970 and 1990. Economic inequality also increased between 1970 and 1990. Using 1970, 1980, and 1990 Census data, I find that an increase in income inequality at the state level is associated with an increased in economic segregation in the state. The increase in segregation was not mainly the result of a decline in within-neighborhood economic heterogeneity. Economic inequality between households in the same census tract hardly changed between 1970 and 1990. The increase in segregation was mainly due to an increase in the variance of mean neighborhood income. This has important implications for interpreting the consequences of increases in economic segregation and for understanding why economic inequality and economic segregation are related.