The National Environmental Policy Act of 1969 requires federally funded projects to be evaluated for environmental impact to determine if a complete environmental impact statement must be prepared. Such an environmental assessment must also be included in any feasibility study for harbor enlargement and bank stabilization measures under the Water Resources Development Act. Population increases, coupled with economic growth from increased agricultural and industrial productivity, have resulted in increased Mississippi River barge transportation needs for Arkansas and Missouri. We report here two such environmental assessments of planned harbor expansions of the New Madrid County and Pemiscot County ports in the Missouri bootheel along the Mississippi River. We evaluated the environmental settings, presence of wetlands, and the presence of hazardous, toxic or radioactive wastes (HTRW) at the two sites. The results of these evaluations were used to determine the possible significant resources and impacts (including endangered species) associated with harbor expansion at the two sites. No significant HTRW were present or likely to be encountered during construction at either site. However, differences in 1) the environmental settings (open high banks vs. bottomland forest), 2) significant resources (historical accounts of least tern colonies at one site), and 3) presence of wetland habitat at one site may preclude or reduce the level of one or both harbor expansions. Careful consideration of possible environmental impacts may help guide the choice of sites for similar harbor expansions in Arkansas