// reducers.js
import { combineReducers } from 'redux'
import { connectRouter } from 'connected-react-router'

export default (history) => combineReducers({
  router: connectRouter(history),
  ... // rest of your reducers
})

// configureStore.js
...
import { createBrowserHistory } from 'history'
import { applyMiddleware, compose, createStore } from 'redux'
import { routerMiddleware } from 'connected-react-router'
import createRootReducer from './reducers'
...
const history = createBrowserHistory()

const store = createStore(
  createRootReducer(history), // root reducer with router state
  initialState,
  compose(
    applyMiddleware(
      routerMiddleware(history), // for dispatching history actions
      // ... other middlewares ...
    ),
  ),
)

...
import { Provider } from 'react-redux'
import { Route, Switch } from 'react-router' // react-router v4
import { ConnectedRouter } from 'connected-react-router'
...
ReactDOM.render(
  <Provider store={store}>
    <ConnectedRouter history={history}> { /* place ConnectedRouter under Provider */ }
      <div> { /* your usual react-router v4 routing */ }
        <Switch>
          <Route exact path="/" render={() => (<div>Match</div>)} />
          <Route render={() => (<div>Miss</div>)} />
        </Switch>
      </div>
    </ConnectedRouter>
  </Provider>,
  document.getElementById('react-root')
)