Glascow, Scotland?
Since Philly is your first US destination, you would have to claim your bags, then go through immigration. There's an area to re-check bags for your connecting flight just after immigration/customs. Keep in mind, since you've had access to your checked baggage, you do need to be re-screened by security. It sounds like a pain, but this is how it was explained to me when I called and asked the airline about where we clear immigration on our way back form Jamaica....we fly into Miami, clear immigration, re-check baggage, re-clear security, and then board our flight for Orlando. How much of a layover to you have for your connection?
