Apart from the lands he himself cultivated, Carter rented or leased a large proportion of his estate to others. He developed an elaborate system of tenancy reminiscent in its principal features of the modern lien system and "share cropping." Lands were leased for varying periods under specific agreements as to the uses to be made of them, the provision of tools and other supplies by the landlord, and the proportion of the crops to be paid as rent. Other tracts were leased for a fixed money rental. To Carter's interests as a planter and a landlord he added those of a manufacturer. When conditions made it economical or necessary to furnish his own supplies, he operated textile factories, salt works, grain mills, and bakeries to fill his own and his neighbors' needs. In his smiths's shops the simple farm implements of the time were forged and repaired, and work was also done for near-by planters. Through his wife's relations he received a one-fifth share in the Baltimore Iron Works. As part owner of this firm he produced bar and pig iron in large quantities on a commercial basis, and incidentally supplied raw materials needed on his plantations. He also carried on extensive operations as a merchant and factor. From his stores at "Nomini Hall," European manufactures and merchandise of every sort were dispensed. He owned a number of vessels which regularly carried supplies to the landings of other planters on the Virginia rivers and the Chesapeake and took their produce off their hands. Sometimes he provided these men with banking and credit facilities. The scope of Carter's activities is indicated by the fact that at one time his slaves numbered over 500. In addition, he employed numerous white stewards, overseers, clerks, skilled craftsmen, and artisans. In a labor force so numerous and diversified the most careful adjustments in human relationships were necessary. In a very real sense Carter acted as a protector, father, physician, and court of last resort for all his people. No complaint was too insignificant to receive the master's consideration.