We explore the relationship between disaggregated trading flows, the Canada/U.S. dollar (CAD/USD) market and U.S. macroeconomic announcements with a novel data set of unprecedented breadth and length. Foreign financial trading flows appear to demand liquidity, contemporaneously driving the CAD/USD while commercial trading flows seem to be price sensitive, providing liquidity in response to exchange rate movements. Despite strong contemporaneous correlations with trading flows, exchange rate returns are generally not predictable, except for some intriguing success at long horizons. This failure contrasts with much, but not all, previous research on the topic. While two types of CAD trading flows and the CAD/USD appear to be cointegrated, such structure is probably spurious. There appear to be structural breaks in the order-flow-exchange rate VECM systems in 1994-1996 and 1998-1999. Data Appendix.