How can we secure a future for the white race?

Because if we can't, then that will be the end of first world civilization in 50 years. As the USA continues to become mongrelized due to the enormous influx of lesser non-white races, the US will become a cesspot of multicultural madness, social decay, and racial disunity. Race crimes will rise, gaps between the rich and poor increase, and social disharmony will be widespread. I am at a loss to explain why white people want to pollute their own gene pool with other races by having mixed marriages. White man obviously lacks a racial consciousness. The downfall of modern civilization is upon us. 90% of all great art, inventions, science, discovery, music, etc has been due to the white race. A dwindling white race will equal widespread unhappiness and rampant crime and corruption. Will the US government wake up, prevent non-white immigration, and thus secure a bright future for the US? Or is it already too late? We all know the best countries to live in have a majority white population.