Each of the fifty states in the United States share certain characteristics: each government is based on a written constitution, which cannot contradict the federal constitution; each has a republican form of government comprised of the same three branches (executive, legislative and judicial) as the federal government and containing a similar system of checks and balances, and separation of powers. Within these broad similarities, however, there can be significant differences in governmental structures among the various states.

A governor heads the executive branch of every state; the governor is in charge of running the government and implementing state laws. The governor's authority includes: developing and proposing legislation to the state legislature; overseeing the state's national guard; calling special sessions of the state legislature; and, pardoning persons convicted of state crimes. The length of a term served by a governor varies but, is usually two or four years. A state governor oversees the state administrative agencies, including those agencies relating to environmental protection, wildlife conservation, or natural resource management.

State Legislatures
Every state has a legislature with two chambers, except Nebraska, which has only one. All state legislatures serve the same purpose: to represent the citizens of the state in making laws concerning state issues. State legislative terms vary, but are typically two or four years. Unlike federal laws, state laws only apply within a state's borders.

State Judiciaries
All state judiciaries are hierarchical, like the federal system. State systems are made up of a Supreme Court (sometimes with a different name), usually an intermediate appellate court, and a series of lower courts or trial courts, sometimes including specialized courts. State judiciaries interpret state laws and apply them in specific disputes relating to state law; they determine whether a state crime has been committed; they evaluate the constitutionality of state laws under the state constitution; and they review the legality of state administrative rules under state statutes.

Local Government
Local governments, unlike state governments or the federal government, are not directly defined by a constitution though many state constitutions determine the process for creating a local government. For example, although many state constitutions determine the process for creating a local government, in many states, the state legislature must vote on the charter for any local government structure. Local government structures may vary, but they typically include counties, cities, villages, and townships. City governments most commonly include an elected mayor, which is the chief executive, and a city council, which acts much like a legislature. Villages and townships are often found in more rural areas; they may have a structure similar to that of a city or be run by a commission. Most states are divided into counties, usually with an elected board of county commissioners or supervisors. There may also be other elected county officials, including sheriffs or county executives. In addition, many special purpose delegates carry out such functions as education and sometimes environmental regulation.

Local governments, including cities and counties, often have important environmental responsibilities, such as managing solid waste, ensuring clean drinking water, developing and enforcing land-use plans, inspecting local restaurants and other establishments for health and safety, and providing emergency services and planning. More generally, local governments have the power to tax, to enact and enforce local ordinances, and to administer the local aspects of certain state and federal programs.

"Native" Governments
Under the United States Constitution, Native Americans supposedly have significant rights of self-government which stem from their own sovereignty. Among other powers, tribal governments have the power to tax, to pass their own laws, and to have their own courts. Nonetheless, the general rule is that federal laws of general applicability apply equally to Native Americans and their property. Exceptions to this general applicability of federal law apply where Congress intended to exempt Native Americans, where the issues relate to the core of Native American self-governance and self-organization, or where application would abrogate rights guaranteed by Native American treaties. Even in these areas, however, Congress can expressly apply a statute to Native Americans.

Many of the federal environmental laws have specific provisions explaining how the law applies to Native American tribal lands. The provisions vary, but typically grant to Native American tribal governments similar rights and responsibilities as those granted to states.