What is the level of state capacity in developing countries today, and what have been its drivers over the past century? We construct a comprehensive new data set of tax and revenue collection for forty-six African polities from 1900 to 2015. Our data show that polities in Africa have been characterized by strong growth in fiscal capacity on average, but that substantial heterogeneity exists. The empirical analysis reveals that canonical state-building factors such as democratic institutions and interstate warfare have limited power to explain these divergent growth paths. On the other hand, accounting for the relationship between African polities and the international environment—through the availability of external finance and the legacy of colonialism—is key to understanding their differing investments in fiscal capacity. These insights add important nuances to established theories of state building. Not only can the availability of external finance deter investment in fiscal capacity, but it also moderates the efficacy of canonical state-building factors.

We examine optimal monetary policy in a New Keynesian model with unemployment and financial frictions where banks produce loans using equity as collateral. Firms and households demand loans to finance externally a fraction of their flows of expenditures. Our findings show amplifying business-cycle effects of a more rigid loan production technology. In the monetary policy analysis, the optimal rule clearly outperforms a Taylor-type rule. The optimized interest-rate response to the external finance premium turns significantly negative when either banking rigidities are high or when financial shocks are the only source of business cycle fluctuations.

We develop a theory of financial development based on the costs associated with the provision of external finance. These costs arise through informational asymmetries between borrowers and lenders that are costly to resolve. When borrowing is limited, producers with access to financial intermediary loans obtain higher returns to investment than other producers. This creates incentives for others to undertake the technology adoption necessary to access investment loans. Over time, as increasing numbers of producers gain access to external finance, borrowers' net worth rises relative to debt. This reduces the costs of financial intermediation and raises the overall return on investment. The theory is consistent with recent evidence that financial development reduces the costs associated with the provision of external finance and increases the rate of economic growth. Furthermore, the theory predicts that financial development will raise the return on loans and reduce the spread between borrowing and lending rates.