Johnnie, there has been a series of good data coming out from the US in the past few months.
Because the US is still the largest economy in the world, the market is reading the series of good news as a positive recovery of the US economy and anticipating it will spur growth in other parts of the world. Hence, you saw the rally in the risk currencies on 15/16 March when the US released good data because investors felt positive about the economic outlook.
To your success as a profitable trader,
P.S. Ask me your most burning Forex question today!