"In which" is not grammatically suitable. If we switch "in" then it will be a grammatically accurate sentence.
Explanation:
The fresh Immigrants In the beginning 1800s, the largest immigrants were Protestants from western and northern Europe. Many talked English and had participation in democracy. By difference, most of the “fresh immigrants” who began to appear in the advanced 1800s came from countries of eastern and southern Europe, such as Russia, Poland, Italy, and Greece. Most were Jewish or Catholic. A less number came from Asia and the Pacific. Few learned English or had practice living in a democracy or a capital.
