Street gangs have a long history in American cities (Thrasher 1927). Until recently, gangs were organized primarily as social peer groups. Any economic activities were of secondary importance (Suttles 1968, Klein 1995). The last two decades, however, have given rise to a dramatic transformation in street gangs, or what Taylor (1990) terms their "corporatization."

Firms' organizational choices are influenced by external conditions such as the instability of the product market. In order to address this issue in a macroeconomic perspective, we embed the firm's choice of organizational structure in a model of growth through creative destruction, which induces endogenous market volatility. We find that an increasing supply of skill or globalization may increase the rate of creative destruction, the skill premium, and the skilled wages, and it may depress the unskilled wages. We use an original data set to test the empirical relevance of our theory.

During the nineteenth century most Western societies extended voting rights, a decision that led to unprecedented redistributive programs. We argue that these political reforms can be viewed as strategic decisions by the political elite to prevent widespread social unrest and revolution. Political transition, rather than redistribution under existing political institutions, occurs because current transfers do not ensure future transfers, while the extension of the franchise changes future political equilibria and acts as a commitment to redistribution. Our theory also offers a novel explanation for the Kuznets curve in many Western economies during this period, with the fall in inequality following redistribution due to democratization.

We study the consequences of hospital competition for Medicare beneficiaries' heart attack care from 1985 to 1994. We examine how relatively exogenous determinants of hospital choice such as travel distances influence the competitiveness of hospital markets, and how hospital competition interacts with the influence of managed-care organizations to affect the key determinants of social welfare—expenditures on treatment and patient health outcomes. In the 1980s the welfare effects of competition were ambiguous; but in the 1990s competition unambiguously improves social welfare. Increasing HMO enrollment over the sample period partially explains the dramatic change in the impact of hospital competition.

College educated couples are increasingly located in large metropolitan areas. These areas were home to 32 percent of all college educated couples in 1940, 39 percent in 1970, and 50 percent in 1990. We investigate whether this trend can be explained by increasing urbanization of the college educated or the growth of dual career households and the resulting severity of the colocation problem. We argue that the latter explanation is the primary one. Smaller cities may therefore experience reduced inflows of human capital relative to the past and thus become poorer.