Bank lending booms and asset price booms are often intertwined. Although a fundamental shock might trigger an asset boom, aggressive lending can push asset prices higher, leading to more lending, and so on. Such a dynamic seems to have characterized the agricultural land boom surrounding World War I. This paper examines i) how banks responded to the asset price boom and how they were affected by the bust; ii) how various banking regulations and policies influenced those effects; and iii) how bank lending contributed to rising farm land values in the boom, and how bank closures contributed to falling prices in the bust. We find that rising crop prices encouraged bank entry and balance sheet expansion in agriculture counties. State deposit insurance systems amplified the impact of rising crop prices on the size and risk of bank portfolios, while higher minimum capital requirements dampened the effects. Further, increases in county farm land values and mortgage debt were correlated with the number of local banks ex ante and increases in bank loans during the boom. When farm land prices collapsed, banks that had responded most aggressively to the asset boom had a higher probability of closing, while counties with more bank closures experienced larger declines in land prices than can be explained by falling crop prices alone.