public static void Main()
<DocumentID>62017836-1</DocumentID>
<DocumentReference type=""CustomerSuppliedReference"">
<Description languageID=""en-us""/>
<ActualShipDateTime>2023-06-07T09:16:33-04:00</ActualShipDateTime>
<ShippingMethod>CHEAPEST METHOD W/FIRST CLASS</ShippingMethod>
<DocumentReference type=""TrackingNumber"">
<TrackingNumber>9200190233107605458375</TrackingNumber>
var doc = XDocument.Parse(xml);
.Elements("DocumentReference")
.Where(e => (string)e.Attribute("type") == "TrackingNumber")
.SelectMany(e => e.Elements("TrackingNumber"))
var result2 = doc.XPathSelectElements(
@"/ShipmentHeader/DocumentReference[@type=""TrackingNumber""]/TrackingNumber")