The website with the largest amount of demographic information is:

The choice of census.gov as the answer is based on its extensive collection of demographic information. The U.S. Census Bureau, which operates the website, is the primary source for data about the population in the United States. It conducts the decennial census, which counts every resident, and collects a wide array of demographic data, including age, race, ethnicity, household composition, and economic status.

Census.gov provides access to detailed reports, data sets, and tools for analyzing this demographic information, making it an invaluable resource for researchers, policymakers, and the general public. This breadth and depth of data surpass what is typically available on other websites focused on demographics or related statistics.

While the other options may provide useful information, they do not specialize solely in comprehensive demographic data like census.gov does. For instance, data.gov serves as a general repository for a wide range of government data, fedstats.gov aggregates information from various federal sources, and demographics.gov may provide specific demographic studies but does not have the comprehensive dataset that the Census Bureau offers.