February 15, 2017
The 2018 interactive Senate map has been updated to include the special election that will be held in Alabama on the general election date of November 6th of that year. The seat became open when Jeff Sessions was confirmed as U.S. Attorney General earlier this month. Alabama Governor Robert Bentley appointed Luther Strange, the state's Attorney General at the time, to fill the seat.
This is a 'Class 2' seat, and will therefore be contested again, for a full six year term, in November, 2020.
With the addition of this special election, 34 Senate seats will be contested in 2018. As a practical matter, this additional race won't change anything in terms of the battle for control. The seat is heavily favored to remain in Republican hands. Democrats must gain three seats to take control. This will be a difficult climb, even if the climate turns more favorable, as only nine of these 34 seats currently have a Republican incumbent.