title: Given latitude/longitude say if the coordinate is within continental US or not
body: <p>I want to check if a particular latitude/longitude is within continental US or not. I don't want to use Online APIs and I'm using Python.</p>
  
  <p>I downloaded <a href="https://www.census.gov/geo/maps-data/data/cbf/cbf_nation.html" rel="nofollow noreferrer">this shapefile</a></p>
  
  <pre><code>from shapely.geometry import MultiPoint, Point, Polygon
  import shapefile    
  sf = shapefile.Reader("cb_2015_us_nation_20m")
  shapes = sf.shapes()
  fields = sf.fields
  records = sf.records()
  points = shapes[0].points
  poly = Polygon(points)
  lon = -112
  lat = 48
  point = Point(-112, 48)
  poly.contains(point)
  #should return True because it is in continental US but returns False
  </code></pre>
  
  <p>The sample lon, lat is within US boundary but poly.contains returns False.
  I'm not sure what the problem is and how to solve the issue so that I can test if a point is within continental US.</p>