req.params undfined

// Setup server
var express    = require('express');
var app        = express();
var path       = require('path');
var db         = require('./db.js');
var bodyParser = require('body-parser');
var methodOverride = require('method-override');

// Tools
app.set('view engine', 'ejs');
app.use(methodOverride('_method'));
app.use(bodyParser.json());
app.use(bodyParser.urlencoded());

// Listen on port
app.listen(3000);
console.log('Server running');

// ROUTE: Homepage
app.get("/", function(req,res) {
  db.query("SELECT * FROM entries", function(err, dbRes) {
    if (!err) {
      res.render('index', { entries: dbRes.rows });
    }
  });
});

// ROUTE: List of all entries
app.get('/entries', function(req,res) {
  db.query('SELECT * FROM entries', function(err, dbRes) {
    if(!err) {
      res.render('entries', { entries: dbRes.rows });
    }
  });
});

// ROUTE: Create a new blog entry
app.get("/new", function(req,res) {
  res.render('new');
});

app.post('/entries', function(req, res) {
  var params = [
    req.body.article_title,
    req.body.article_body,
    req.body.article_tags
  ];

  db.query(
    "INSERT INTO entries (article_title, article_body, article_tags) VALUES ($1, $2, $3)", params, function(err, dbRes) {
      if (!err) {
        res.redirect('/');
      }
    }
  );
});

// ROUTE: View an entry
app.get('/:id', function(req, res) {
  console.log(req.params);
  db.query("SELECT * FROM entries WHERE id = $1", [req.params.id], function(err, dbRes) {
    if (!err) {
      res.render('show', { entry: dbRes.rows[0] });
    }
  });
});