// webpack.config.js
new Webpack.DefinePlugin({
  BASENAME: '/users'
})

// somewhere in your application
import { useRouterHistory } from 'react-router'
import { createHistory } from 'history'

const history = useRouterHistory(createHistory)({
  basename: BASENAME
})

plugins: [
    new webpack.DefinePlugin({
      BASENAME: JSON.stringify("/")
    })
  ],

plugins: [
    new webpack.DefinePlugin({
      BASENAME: JSON.stringify("/users/")
    }),

import { Router, Route, IndexRoute, browserHistory } from 'react-router';
import { useBasename } from 'history'
...
<Router history={useBasename(() => browserHistory)({ basename: BASENAME })}>