The months of December 2017 through to January 2019 have been associated with declining smartphone sale numbers in the United States on a year-on-year basis. Counterpoint, a market analysis firm, cited the lack of deals on flagships and the government shutdown as factors in the trend as it applied to January.
https://www.notebookcheck.net/The-US-market-has-seen-14-consecutive-months-of-falling-smartphone-sales.415058.0.html