This paper first reveals the basic properties behind the spatial concentration measurement when using “employment Lorenz curves”. This involves axioms adapted not only from the literature on income distribution but also from that on occupational segregation. Second, additive decompositions of this curve by subsectors and by groups of locations are proposed since, as far as we know, no decompositions of these curves have yet been suggested in the field. This approach is finally used to analyze the concentration of the Spanish manufacturing industry. In particular, we study whether the technological intensity of an industry affects the extent of its spatial concentration level.