THIS: A shutdown that lasts two weeks or more would probably start to slow an already sluggish economy, analysts say. Closures of national parks would hurt hotels, restaurants and other tourism-related businesses. And federal workers who lost pay would spend less, thereby curbing economic growth. A three-week shutdown would slow the economy's annual growth rate in the October-December quarter by up to 0.9 of a percentage point, Goldman Sachs has estimated. If so, that could mean a growth rate of 1.6 percent, compared with the 2.5 percent that many economists now forecast.