A record of the R.O.W. McManus mill was found in the 1860 special census of Liberty County by W.T. Block of Nederland. According to the Census, the mill was steam powered and employed four workers during the census year 1860. The mill cut 50,000 feet of lumber worth $1,200 from $75.00 worth of sawlogs. McManus paid $75.00 monthly in wages. The d capital value was $3,000.
Webb, in the Handbook of Texas, recorded that Moss Bluff was settled before the Revolution and that it had both sawmills and gristmills by 1840. After the Civil War, the economy shifted to rice and cotton.
This mill is usually linked in discussion with that of Dr. Gillard.