title: How to set line width and color when plotting a shapefile with plot()
body: <p>I have a simple shapefile I want to plot with the general plot() (I noticed that ggplot is extremely slow in plotting maps). </p>
  
  <p>I can correctly plot the shape with the code</p>
  
  <pre><code>library(maptools)    
  map_shp &lt;- readShapePoly(map_filepath)
  map &lt;- fortify(map_shp)
  plot(map)
  </code></pre>
  
  <p>But how could I define the color and width of the lines?</p>