Union membership displayed a ∩-shaped pattern over the 20th century, while the distribution of income sketched a ∪. A model of unions is developed to analyze these phenomena. There is a distribution of firms in the economy. Firms hire capital, plus skilled and unskilled labor. Unionization...

An endogenous growth model is developed where each period firms invest in researching and developing new ideas. An idea increases a firm's productivity. By how much depends on how central the idea is to a firm's activity. Ideas can be bought and sold on a market for patents. A firm can sell an...