The Unassuming Economist

From a new VOX post by David Autor:

“Labour markets in US cities today are vastly more educated and skill-intensive than they were 50 years ago, but urban non-college workers now perform much less skilled work than they did. This column shows that automation and international trade have eliminated many of the mid-skilled non-college jobs that were disproportionately based in cities. This has contributed to a secular fall in real non-college wages.”

“Figure 2 depicts the aggregate relationship between population density and occupational structure at the level of 722 commuting zones (CZs) covering the contiguous US states between 1970 and 2015.

The three panels of this figure report the CZ-level share of employment among working-age adults into the three broad occupational categories described above: traditionally low-education, low-wage services, transportation, labourer, and construction workers; traditionally mid-education, middle-wage occupations made up of clerical, administrative support, sales, and production workers; and high-education, high-wage, professional, technical, and managerial workers.

The horizontal axis is the natural log of population density (the number of residents divided by CZ land area). For consistency, I used each zone’s population density in 1970 throughout, and the data are weighted by the count of working-age adults in each CZ. Each plotted point in the bin-scatter represents approximately 5% of all workers in each year.

The rising set of upward-sloping curves in the right panel show that while denser CZs have traditionally been more intensive in high-skill work, the level and slope of this relationship between density and skill-intensity has risen consistently over multiple decades. The overlapping downward-sloping curves in the left panel show that the fraction of workers engaged in low-skill occupations has historically been much smaller in high-density CZs, and this pattern has changed little over decades. In the middle panel, the fan-shaped set of curves show that the denser CZs were exceptional in the 1970s for having far more middle-skill work than suburban and rural CZs. But this exceptional feature attenuated. By 2015, the densest CZs had less middle-skill work than the suburbs or rural areas.”