Data available through MARIS is FREE
You need ESRI software or some other software that can read ESRI formatted data.
Although the MARIS web site is designed for a general audience, the data that are available for direct downloading are intended for persons that have some familiarity with geographic information systems (GIS) - especially in terms of geographic projections, mapping, and software.
The standard projection for all vector data distributed is the Mississippi Transverse Mercator. MSTM
The available format, ESRI Shapefiles, is those most frequently used in Mississippi state government and is the most commonly requested overall. If you need these data in another format, require additional assistance, or have any other questions, please feel free to contact the MARIS Technical Center. EMAILCustom Download USGS Quad Index