| Good Ol' Time Racing Association -- GOTRA is a vintage dirt modified racing organization for racing coupes and sedans dated 1928 through 1948. |
| I.M.C.A. -- International Motor Contest Association, based in Vinton, Iowa. Classes include modifieds, late models, sprint cars, stock cars and hobby stocks. |
| NEI Dirt Tour -- Northeast Iowa Dirt Tour features the dirt modified drivers and events. |
| OMDA -- Ohio Modified Drivers Association, focusing on modified cars and oval track racing events in Ohio. |
| S.M.A.R.T. -- Southern Modified Auto Racing Teams sanctioning body, based in Kernersville, North Carolina. |
| Small Block Owner and Drivers Association (SMODA) -- Information on membership. |
| United Midwestern Promoters -- UMP is an open wheel modified sanctioning body. |
| USA Modifieds -- News, schedule, driver profiles, point standings and rules. |
| USMTS -- United States Modified Touring Series, including forum, schedule, results, points, and driver information. Also includes information about the United States Racing Association. |
| York Series -- York Triathlon Modified Racing Series. |
