I want throw this out for those who might get confused. As Jerry Coffee says in his postings, the Ft Smith-Boggy Depot road was part of the Butterfield Overland Mail Route (Stage Line) and is sometimes called "the Line Road". The Butterfield was only in operation about 2 or 3 years but there was still a stage and mail on this route until the railroads made it uneconomical.
In reading the ORs about Indian Territory and Arkansas, you will run across a great many references to the "Line Road" that refer to stateline road along the western boundary of Arkansas. This road came from Missouri south through Maysville to Van Buren and Ft Smith and south through Dallas (Panther) to Laynesport at the Red River.
Another thing to watch out for is the Telegraph Road at Pea Ridge AR was also part of the Butterfield Route and was called the "Line Road" as it ran down through Fayetteville through the Boston Mtns to Van Buren and Ft Smith.
So... I've learned the hard way, you have to really watch the context to make sure you know where they are talking about. There are multiple Line Roads, Ft Smith Roads, Texas Roads, California Roads, Sulphur Springs, Dripping Springs, Double Springs, Dallas TX and Dallas AR...
There's Ft Arbuckle and Old Ft Arbuckle and Camp Arbuckle and the other Old Ft Arbuckle... etc etc