In the span of a few decades, Los Angeles area construction went from an industry that was two-thirds white, and largely unionized, to one that is overwhelmingly Latino, mostly nonunion and heavily reliant on immigrants, according to a Los Angeles Times review of federal data.

At the same time, the job got less lucrative. American construction workers today make $5 an hour less than they did in the early 1970s, after adjusting for inflation.

Today slightly more than 1 in 10 construction workers are in a union, compared with 4 in 10 in the 1970s.