Spatial segregation of low- and high-wage workers is a persistent economic issue with broad social implications. Using social security data and an AKM wage decomposition, this paper examines spatial wage inequality in West Germany. Spatial inequality in log wages rose sharply between 1998 and 2008, mainly due to increased variance in worker pay premiums across regions (48%) and stronger positive spatial assortative matching of workers and establishments (40%), i.e. colocation. Changes in establishment wage premia are mostly unrelated to rising colocation whereas labor mobility even reduced it. Instead, growth in worker pay premiums among stayers was concentrated in regions where high-wage workers and high-wage establishments were overrepresented already in the 1990s and, thus, magnified pre-existing colocation leading to ‘colocation without relocation’. Germany’s rising trade surplus, especially with Eastern Europe, boosted stayers’ worker pay premiums in those ex-ante high-wage regions and fully explains rising colocation.

The three articles in this special issue on “Monopsonistic Labour Markets” provide novel insights on how to model the reasons for employers’ monopsony power, how to measure it, and how much of it materialises in lower wages. We are confident that the studies published in this issue will be of high interest to specialists and a broader audience of economists alike. They definitely deserve a wide readership, and our not unwarranted hope is that they will provide new impulses to those partaking in the monopsony literature.