How can a government build a unified nation out of a people with diverse interest and concerns?

The first and most important thing to establish a government when diversity is an issue is compromise. In The Constitution compromises were made. These included the Three-Fifth's Compromise and the Connecticut Compromise. Also, you must give the people what they want. Otherwise a government cannot last. They failed to preserve the rights of humans in The Constitution and some states refused because of that. The Bill of Rights was written as soon as the government truly came into being to please the people. Finally, a government must be given the power to override the citizens if the need arises. Without this, emergencies could arise and without these overrides, the government would be powerless to aid it's citizens. One of these overrides is the warrants that the police and higher offices of justice and national security use to search houses and arrest citizens.