A wider trade deficit is a pretty big part of the blame. I guess trade deficits matter after all.
http://www.marketwatch.com/story/us-economy-slows-to-19-in-4th-quarter-gdp-shows-2017-01-27
http://www.marketwatch.com/story/us-economy-slows-to-19-in-4th-quarter-gdp-shows-2017-01-27