This now makes 25 states, or half, in total.
The state beginning the early voting process today is Missouri.
Note from me - I will also point out that of the 5 most populous states, only Texas (#2) and Pennsylvania (#5) are participating in early voting at this stage, demonstrating how completely unnecessary this nonsense is.
Most populous states and their early voting starts:
CA - Pop. +39 Million, October 3rd
TX - Pop. +29 Million
FL - Pop. +21 Million, October 2nd
NY - Pop. +19 Million, October 1st
PA - Pop. +12 Million
For those keeping track
Mailed out ballots:
North Carolina -9/4
Kentucky - 9/14
Wisconsin - 9/17
Arkansas - 9/18
Minnesota - 9/18
South Dakota - 9/18
West Virginia - 9/18
Alabama - 9/19
Delaware - 9/19
Georgia - 9/19
Idaho - 9/19
Indiana - 9/19
Louisiana - 9/19
Michigan - 9/19
New Jersey - 9/19
Oklahoma - 9/19
Pennsylvania - 9/19
Rhode Island - 9/19
Tennessee - 9/19
Texas - 9/19
Vermont - 9/19
Virginia - 9/19
Wyoming - 9/19
Missouri - 9/22
Began in-person early voting:
Pennsylvania - 9-14
Minnesota - 9/18
South Dakota - 9/18
Virginia - 9/18
Wyoming - 9/18
Michigan - 9/19
New Jersey - 9/19
Vermont - 9/19
And these 25 states have begun this process without the benefit of having a single presidential debate beforehand.
It should be noted that President Trump requested multiple times to have the debate schedule moved up, but his opponent and the debate commission both declined to accommodate his requests.