He received an honorable discharge in June 1815 and resumed his legal studies under William Wirt in Norfolk, Virginia.
[3] Preston had a great interest in developing better transportation throughout the south and was a promoter of a railroad from New Orleans to Jackson, Mississippi.
He also pursued charitable interests and gave land for the Methodist Episcopal Church in Carrollton in 1843.
After Catherine's death in 1842, he married again to Margaret Hewes, the widow of his father-in-law, in 1845.
He died in the explosion of the steamboat St. James on Lake Pontchartrain which was engaged in a race from Biloxi, Mississippi to New Orleans.