title: ModelState Not Valid for Blank Html.DropDownList
body: <p>I have a form with a dropdownlist with a blank selection. I want the user to be able to enter a blank selection if they want. But, the model state comes back as invalid for the CountryID. Any help will be appreciated.</p>
  
  <p>Create.cshtml:</p>
  
  <pre><code>@(Html.DropDownList("CountryID", Model.Countries, ""))
  </code></pre>
  
  <p>Office.cs:</p>
  
  <pre><code>public class Office
  {
      public Office()
      {
      }
  
      public Office(Int32 SyncID, string OfficeName)
      {
          this.SyncID = SyncID;
          this.OfficeName = OfficeName;
      }
  
      public Int32 OfficeID { get; set; }
      public Int32 SyncID { get; set; }
      public Int32 OfficeRollupID { get; set; }
      public Int32 StateProvID { get; set; }
      public Int32 CountryID { get; set; }
      public bool Active { get; set; }
  
      [Required]
      [Display(Name="Office Name")]
      public string OfficeName { get; set; }
  
      [Display(Name = "Office Rollup")]
      public IEnumerable&lt;SelectListItem&gt; OfficeRollups { get; set; }
  
      [Display(Name = "State/Province")]
      public IEnumerable&lt;SelectListItem&gt; StateProvinces { get; set; }
  
      [Display(Name = "Country")]
      public IEnumerable&lt;SelectListItem&gt; Countries { get; set; }
  
      public List&lt;SquareFootage&gt; SquareFootages { get; set; }
  }
  </code></pre>
  
  <p>HomeController.cs:</p>
  
  <pre><code>[HttpPost]
  public ActionResult Create(Office model)
  {
      if (ModelState.IsValid)
      {
          //db.SaveChanges();
  
      }
  
      return View(model);
  }
  </code></pre>