The R package webmap creates interactive web maps using the JavaScript Leaflet library with base layers of The National Map (TNM). Map service endpoints are offered with no use restrictions and provide access to base geospatial information that describes the landscape of the United States and its territories. Base layers outside these areas are unavailable at higher spatial scales. This package is dependent on, and intended to be used with, the Leaflet for R package. Various utility functions are included that allow you to augment your web map with additional elements.