Immigration through industrialisation. Especially in the 'Guilded Age'. But beware! Under the influence of mass immigration, democracy as fought for in the American Revolution had already turned to 'Liberal Democracy', meaning 'power to the elite'. This showed in curtailing voting rights of the poor, illiterate, criminals, foreigners, people of African decent, people without a fixed address, people who had received government support, etc. Usually, this was to ' fight fraud' (sound familiar?).
