How react-router-redux pass initial state?

Question

With react-router-redux, I have the Code:

const reducers = combineReducers({
  ...counterReducer,
  routing: routerReducer
})

const store = createStore(reducers, {initialState: 10})
const history = syncHistoryWithStore(browserHistory, store)

console.log(store.getState())

The output like:

why I don't get the {initialState: 10} in the state ?