I’m wondering how long it takes for a letter to travel through the US Postal Service. I’m sending a letter to a friend who lives in another state and I’m not sure how long it will take for them to receive it. I’m hoping to get an answer from someone who has experience with sending mail through the USPS. Is there anyone out there who can tell me how long it usually takes for a letter to travel through the USPS? Any advice would be greatly appreciated.