What impact did the films of D.W. Griffith have on culture?

Aside from the
ongoing political debates that D.W. Griffith's films fed into, and
off of, his major impact on culture is that of the Feature Film, or a standalone, long-form film
instead of shorts or series. Griffith also pioneered or invented many filmic techniques that are
still used today.

From a political standpoint, Griffith's landmark work
Birth of a Nation (1915) was the first to have a major impact on culture.
At the time of release, the Ku Klux Klan had become a mostly fringe
group, without popular support; the massive success of Nation allowed the
Klan to reform as a politically and culturally influential force. Bolstered by public support
from President Woodrow Wilson, the Klan was able to shape the civil
rights debate for the next fifty years, helping keep Jim Crow laws in place and keeping blacks
segregated and marginalized.

From a filmic standpoint,
Nation was the first "blockbuster" film, successful across the
country, and endorsed by the President. It created or standardized techniques such as the
fish-eye lens view, the close-up, and expensive special effects, which before that time were
limited in scope. Running over three hours, it set a standard for long films instead of shorts;
until the rise of television, feature films became the norm for film entertainment, with
serialized films running even longer. It became normal for people across all classes to have
seen and appreciated the same work, instead of seeing only locally-produced films, and no other
film of Griffith's has had the same impact (not even Intolerance (1916),
which he released to placate audiences who criticized Nation as
racist).