A methodology for estimating non-line/area mobile source emissions for a particular study region is developed. This technique employs St. Louis, Mo., regional highway network information in conjunction with EPA emissions procedure model. The methodology is used to calculate carbon monoxide, hydrocarbon, nitrogen oxide, particulate, and sulfur dioxide emissions in the St. Louis Air Quality Control Region under various time of day/day of week combinations. (4 diagrams, 6 references, 7 tables)