US gross domestic product (GDP) grew at an annualized rate of 3.2 per cent in the fourth quarter of 2013, the Commerce Department's Bureau of Economic Analysis reported Thursday.However, despite a strong second half, growth for the full year slowed to 1.9 per cent, from 2.8 per cent in 2012 based on annualized rates for the first three quarters at: 1.1 per cent in the first; 2.5 per cent in the second; and 4.1 per cent in the third.The 2013 slowdown was attributed, in part, to a large decrease in federal government spending when an austerity budget took effect in March.Slower growth in personal consumption, commercial fixed investment and export growth were additional factors weighing on the economy, the bureau said.The year saw GDP - the output of all goods and service produced by labor and property in the United States - exceed 17.1 trillion dollars in the world's largest economy. The GDP report followed Wednesday's decision by the US Federal Reserve to continue tapering its quantitative easing, reducing monthly purchases of government-backed bonds from 75 billion to 65billion dollars starting in February.