The "unlocked" smartphone market has been growing rapidly across the United States in recent years. It posted a +20% YoY growth during Q4 2017 mainly thanks to newly launched products from Motorola, Blu, and Samsung etc. However, unlocked smartphones posted -1% annual decline in 2017, mainly due to weaker performance during the first half of last year, lower iPhone Upgrade Program adoption curve, as well as lengthening replacement cycle in open market. Apple regained the leading position this quarter mainly thanks to the replacement sales of iPhone Upgrade Program. Blu and Motorola almost tied and followed Apple. Samsung, TCL-Alcatel and LG are also among the major players in this category. Our extensive report contains quarterly unlocked smartphone shipments and marketshare for the top 15 vendors in the United States from 2013 through Q4 2017. The report also contains US unlocked smartphone forecasts, as well as unlocked iPhone forecasts from 2012 through 2022. This report is a valuable tool for mobile stakeholders who want to size the fast-growing, high-value unlocked smartphone market in US.