Complex sentence: Martin remained in office as a Democrat until his death in 1929; the district became more competitive for the Republicans later in the 20th century, in 1972 electing Dave Treen Louisiana's first Republican congressman since Reconstruction.
Split into simpler sentences: Martin remained in office as a Democrat until his death in 1929. The district became more competitive for the Republicans later in the 20th century, in 1972 electing Dave Treen Louisiana's first Republican congressman since Reconstruction.