CREATE TABLE table_19166 ("State" TEXT, "Highest point" TEXT, "Highest elevation" TEXT, "Lowest point" TEXT, "Lowest elevation" TEXT, "Mean elevation" TEXT)

what's the highest point with lowest point being belle fourche river at south dakota border
SELECT "Highest point" FROM table_19166 WHERE "Lowest point" = 'Belle Fourche River at South Dakota border'
SELECT "Highest point" FROM "table_19166" WHERE "Lowest point" = 'Belle Fourche River at South Dakota border'