How did andrew carnegie contribute to the industrial development of the united states? responses

how did andrew carnegie contribute to the industrial development of the united states? responses he adopted new techniques to mass-produce steel at a lower cost. he adopted new techniques to mass-produce steel at a lower cost. he supported labor unions and raised his workers’ wages. he supported labor unions and raised his workers’ wages. he introduced pipelines instead of railroad cars to transport oil. he introduced pipelines instead of railroad cars to transport oil. he financed the first transcontinental railroad, allowing rail travel coast to coast.