Manually map an area-specific route

RouteCollectionAreasExtensions.cs

public static class RouteCollectionAreasExtensions
{
    public static Route MapAreaRoute(
        this RouteCollection routes,
        string areaName,
        string routeName,
        string url,
        object defaults = null,
        object constraints = null,
        string[] namespaces = null)
    {
        // Null-checks for: routes, areaName, routeName, url

        var route = routes.MapRoute(
            routeName,
            url,
            defaults: defaults,
            constraints: constraints,
            namespaces: namespaces);

        route.Defaults["area"] = areaName;
        route.DataTokens["area"] = areaName;

        if (namespaces != null && namespaces.Any())
        {
            route.DataTokens["UseNamespaceFallback"] = false;
        }

        return route;
    }
}