This article shows how the Northeastern urban Republican elites in power who tried to reform the Democrat-controlled South after the Civil War were surprisingly deeply influenced by the expansion to the West.The precise analysis of federal electoral laws reveals that the Republican leaders had to face not only the Democrats, but also the Western politicians from their own party who tried to defend very different economic interests.The Republican unity was thus maintained at the price of uneasy tradeoffs of ideology and sectional interests.This maneuvering powerfully contributed to the failure of Reconstruction,and with it of the Civil Rights African-Americans would have to conquer a century later.