Success or failure in freshman algebra has long been thought to have a strong impact on subsequent high school outcomes. We study a remedial algebra policy implemented by the Chicago Public Schools (CPS) for cohorts entering high school in 2003 and 2004. Students scoring below the national median on an eighth grade exam were assigned in ninth grade to a double-dose algebra course, which doubled instructional time and increased tracking by ability. This assignment rule allows difference-in-difference and regression discontinuity estimates of average and local average treatments effects. Using longitudinal data that tracks students from eight grade to college enrollment, we confirm prior work showing positive short-run impacts on freshman GPA, passing rates and math scores. We show long run positive and substantial impacts of remediation on college entrance exam scores, high school graduation rates and college enrollment rates. This is the first evidence we know of to demonstrate long run impacts of remediation in an American urban high school setting.