The nancial architecture prior to the recent nancial crisis was a system of mobile collateral. Safe debt, whether government bonds or privately-produced bonds, i.e., asset-backed securities, could be traded, posted as collateral, and rehypothecated, moving to its highest value use. Since the nancial crisis, regulatory changes to the nancial architecture have aimed to make collateral immobile, most notably with the BIS \liquidity coverage ratio" for banks. We evaluate this immobile capital system with reference to a previous regime which had this feature: the U.S. National Era.