B & O
S W RR
The Baltimore and Ohio Southwestern Railroad operated in the States of Ohio, Indiana, Illinois, and Kentucky. I do not regularly post manuscript cancels on this site because most off document examples are indecipherable and uninteresting. But this one is very clear.
The Baltimore, Ohio and Southwestern Railroad ceased to exist as a separate entity in 1900 and was absorbed into the parent Baltimore & Ohio.
Cowen was President of the B&O at the time the B&O and SW was absorbed into the parent company. John Cowen would pass away in 1904 at the home of his sister in Chicago when he was 59 years old.