I don't have enough reputation to add a comment or make changes, so I will just add this as an answer. The marked answer does not provide an adequate explanation of the answer and confuses some people. It assumes a default home controller because it does not explicitly specify a controller and will not work for all situations where another controller is defined for this area. There are many overloads for Redirect, but the easiest way to achieve the stated goal is:
return RedirectToAction("Action", "Controller", new { id=YourId, Area="AreaName" });
Other answers to this post correctly rewrote the source code, but also did not pay attention to the fact that you need to specify the controller in most situations.
An anonymous object acts as a package for mapping MVC routes to match all route values that you can include in your redirects.
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