collecting statistical information about the population of a country as a whole ( aside from just the headcount ) has an enormous number of uses.
on race, here is from FAQ
Asked since 1790. Race is key to implementing many federal laws and is needed to monitor compliance with the Voting Rights Act and the Civil Rights Act. State governments use the data to determine congressional, state and local voting districts. Race data are also used to assess fairness of employment practices, to monitor racial disparities in characteristics such as health and education and to plan and obtain funds for public services.
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Человек, который почувствовал ветер перемен, должен построить не щит от ветра, а ветряную мельницу