Census Flow Mapper
from the site:
To help users understand and interact with these statistics, the Census Bureau has developed an online mapping tool called Census Flows Mapper. This application allows users to select a county in the U.S. and view the outbound, inbound and net migration flows for that county. Additionally, users can choose flows based on characteristics such as age, sex, race or Hispanic origin.
The application also allows users to download data, zoom in and out on the map to an area of interest, view additional statistics of the selected county and save their map as a PDF file.