The about page talks a bit about the sources. Everything comes from the latest 5-year American Community Survey (ACS), which is part of the Census Bureau's data

The about page talks a bit about the sources. Everything comes from the latest 5-year American Community Survey (ACS), which is part of the Census Bureau's data collection. Data from that survey is in some sense an average over the years of the survey. They use that wide a window to get the error bars down on the various metrics. The exception is the city block level data. The ACS does not publish on the block level, so we fall back on the 2010 census. This is why the individual blocks have way less data. No, we don't have past data.