How did the transcontinental railroad america become a “salad bowl”

Immigrants brought with them different languages, foods, religions, and customs. They made America a diverse country with many ethnicities, like a "salad bowl" (formerly called "the melting pot"). They exercised their right to vote and helped make political changes. Immigrants made major contributions to the growth and development of the United States (Transcontinental Railroad, Andrew Carnegie, and Alexander Graham Bell) and supplied a great part of the labor (work) force.