During the gilded age the us population rose from 15 million in 1830 to nearly 30 million in 1850. from 15 million in 1830 to nearly 40 million in 1870. from nearly 40 million in 1870 to nearly 80 million in 1900. from nearly 40 million in 1870 to nearly 120 million in 1930.

During the Gilded Age the US population rose from from nearly 40 million in 1870 to nearly 80 million in 1900. To add, the Gilded age was a time in between the Civil War and World War I. During this time, the population together with the economy grew rapidly. However, political corruption and corporate deceptions were also rampant during this time, with the wealthy people largely benefiting from this. 

Answer is mass marketing.

Sorry i dont know hope you do good can you mark me as brainlist