The answer to the question in the title is: A lot. In this essay, I argue that the history of macroeconomics during the 20th century can be divided in three epochs: Pre 1940. A period of exploration, where macroeconomics was not macroeconomics yet, but monetary theory on one side, business cycle...

A Monetary History of the United States 1867 to 1960 published in 1963 was written as part of an extensive NBER research project on Money and Business Cycles started in the 1950s. The project resulted in three more books and many important articles. A Monetary History was designed to provide...

The British North American colonies were the first western economies to rely on legislature-issued paper monies as an important internal media of exchange. This system arose piecemeal. In the absence of banks and treasuries that exchanged paper monies at face value for specie monies on demand,...

We identify the major public debt overhang episodes in the advanced economies since the early 1800s, characterized by public debt to GDP levels exceeding 90% for at least five years. Consistent with Reinhart and Rogoff (2010) and other more recent research, we find that public debt overhang...

We provide new evidence on the response of real interest rates and inflation to monetary shocks. Our measure of monetary policy shocks is based on unexpected changes in interest rates over a 30-minute window surrounding scheduled Federal Reserve announcements. Our estimates indicate that nominal...

We characterize the optimal sequential choice of monetary policy in economies with either nominal or indexed debt. In a model where nominal debt is the only source of time inconsistency, the Markov-perfect equilibrium policy implies the progressive depletion of the outstanding stock of debt,...

This paper explores several issues concerning a possible zero lower bound (ZLB) including its theoretical rationale; the magnitude of effects of low sustained inflation on real interest rates; the validity of analyzing monetary policy in models with no monetary variables; and the dynamic...

This paper relates predictable gains from positions in fed funds futures contracts to violations of the expectations hypothesis of the term structure of interest rates. Although evidence for predictable gains from positions in short-horizon contracts is mixed, we find that gains in longer...

Woodford (2003) describes a popular class of neo-Wicksellian models in which monetary policy is characterized by an interest-rate rule, and the money market and financial institutions are typically not even modeled. Critics contend that these models are incomplete and unsuitable for...

This paper examines changes over time in the importance of the lending channel in the transmission of monetary shocks to the real economy. We first use a simple extension of the Bernanke-Blinder model to isolate the observable factors that affect the strength of the lending channel. We then show...