Layer Groups Let’s suppose you have a bunch of layers you want to combine into a group to handle them as one in your code: var littleton = L.marker([39.61, -105.02]).bindPopup('This is Littleton, CO.'), denver = L.marker([39.74, -104.99]).bindPopup('This is Denver, CO.'), aurora = L.marker([39.73, -104.8]).bindPopup('This is Aurora, CO.'), golden = L.marker([39.77, -105.23]).bindPopup('This is Gol