Final answer:
The United States has a greater percentage of Roman Catholics in its population compared to Canada, Russia, or Japan, with 60 million Americans being Roman Catholic and it being the largest religious group in the country.
Step-by-step explanation:
When comparing the countries listed, it is evident that Roman Catholicism is practiced by a greater percentage of the population in the United States than in Canada, Russia, or Japan. About 60 million Americans are Roman Catholic, making it the largest religious group in the United States. This is particularly noticeable in regions such as New England, around the Great Lakes, and along the southern border. The rich Catholic presence in the US is largely attributed to historical immigration from Roman Catholic countries in Europe during the 19th and early 20th centuries and more recently, Hispanic immigrants.
Canada, Russia, and Japan all have less significant percentages of Roman Catholic populations when compared to the United States. In the case of Russia, state-sanctioned atheism during the Soviet era has resulted in a predominantly Russian Orthodox Christian majority, with only about two percent practicing Catholicism. Canada and Japan have lower percentages of Catholics compared to the US as well, with 42 percent and 49 percent of their populations respectively considering religion an important part of their lives, which is less than the 65 percent in the United States.