[throwaway1584]

A pretty straightforward explanation is that ⅔ [1] of the tech workers in Silicon Valley are immigrants. Silicon Valley recruits outliers from around the world, and it doesn't make sense to apply US demographics to an industry that recruits from such a pool.

If you assume that the Silicon Valley percent of immigrant workers holds for Google you conclude that 6% of the American Googlers are African Americans, since none of the foreigners can be. About 2.4% [2] of computer science degree recipients in the US are African American.

[1] https://jointventure.org/images/stories/pdf/index2018.pdf

[2] https://cra.org/crn/2015/09/expanding-the-pipeline-the-state...