On Friday, the Chicago Cubs defeated the Milwaukee Brewers 5-4 in extra innings at Wrigley Field. Miguel Montero hit a walk-off home run to give the Cubs the win.
Chicago is the first of the 6 division winners to capture their division crown. The Chicago Cubs won the NL Central. Home field in the NL will go through Chicago most likely. You cannot say the same for the World Series though as the AL Champion will have home field against the Cubs in the 2016 World Series.
The magic number to lock up home field is 9. The Cubs are 9 games away from securing home field in the National League as the Washington Nationals are the closest team with the best chance of keeping the Cubs from getting home field. I cannot see anyone keeping the Cubs from getting home field at this point in the National League.