This is the United STATES, a democratic republic - not to be confused with a popular democracy outright. We recognize that in national issues, a few blocks in a major city should not be able to out-vote (and thus overrule) entire states having very different needs/interests. Issues which are appropriate for popular vote should be decided within suitably local jurisdictions. Without this balancing of "tyranny of the majority" vs "tyranny of the minority", low-population states would not have signed onto, and would not remain in, the overall federal system.
In a country so large and with so much diversity (!), no region should be able to absolutely dominate another simply by having a larger population.
In a country so large and with so much diversity (!), no region should be able to absolutely dominate another simply by having a larger population.