Impact of US Constitution's Commerce Clause

Introduction
The Commerce Clause is a provision in the U.S Constitution (Article 1, Section 8) that gives Congress the mandate to regulate business with other Nations, States, and Indian Tribes. The commerce clause is the legal foundation of much of Congress's regulatory power (Rosenbaum, Rutkow, & Vernick, 2011). The sovereignty and the exclusivity of the federal government power when dealing with foreign countries and commerce regulation is largely understood. In the past, states and local authorities have been barred by the court from dealing in foreign policy matters because only they have the mandate to deal with those kinds of matters. Although states are grated with some limited powers to tax foreign commerce, the federal government remains the sole agent of Americans in dealings with foreign states.
Power to regulate
Commerce is not defined in the commerce clause or even in the Constitution; hence the courts have various interpretations of the words. The "selective exclusiveness" rule was clearly explained in Southern Pacific Co. v. Arizona (1945). The court stated that Congress has no conflicting regulation, then the state has a residual power to make laws governing locally. In this case, the court came up with a three-part test to determine the implied condition to regulate interstate commerce: (1) that the law allows the state to interfere with the interstate commerce, (2) the commerce under consideration does not in any wat require national or uniform regulation, and (3) that the federal government has no overriding interest in the regulation (Ablavsky, 2014).
Intrastate, or domestic, commerce is a trade that only takes place within one state. Since business activity only takes place with one state's confines, the power to regulate commercial activity stays exclusively in the state's control. Interstate commerce involves trade among several states (Rosenbaum, Rutkow, & Vernick, 2011). The aim of designing the Commerce Clause is to help reduce the intense conflict between different states. Congress's regulatory mandate has increased progressively with the development and expansion of industry and means of transportation.
Although the U.S constitution restricts state power, the state states enjoy certain rights under the Tenth Amendment. A state reserves the right to regulate its domestic commerce; however, Congress still can regulate such commerce in certain situations. 
A good example is in Swift & Co. v. the United States, whereby the court held that a price-fixing system among Chicago meatpackers created a limitation of interstate commerce; hence, the court viewed it as illegal the local meatpacking industry formed part of the current of commerce among the States. The court is tasked with deciding on the national or local character of the subject of regulation by assessing the national interest against the State interest in the subject.
Business Affecting Commerce
The commerce clause directs the federal government to exercise power and regulate commerce and business activities. Since the Constitution's founding up to 1900, more than 1400 cases were heard by the Supreme Court. Most of these cases stemmed from issues with local state laws directing local commerce and trade activities. Most of the Supreme Court rulings before the 1900s restricted the state powers to regulate inter-state business and uphold inter-state commerce activities (Legal Information Institute, 2020). As a result, the term "commerce" governed the rulings, while the term "regulate" was largely overlooked. However, the paradigm shifted in the 1930s, and most rulings post-1930's limited the Power of Congress when it came to business and commerce activity occurring in a single state. By and large, the Constitution's "Commerce Clause" has developed the United States into a single economic and financial unit that promotes the inter-state transfer of merchandise, commerce and business, and individuals.


References
Ablavsky, G. (2014). Beyond the Indian commerce clause. Yale LJ, 124, 1012.
Knoll, M. S., & Mason, R. (2019). The Dormant Foreign Commerce Clause After Wynne. Va. Tax Rev., 39, 357.
Rosenbaum, S., Rutkow, L., & Vernick, J. S. (2011). The U.S. Constitution's Commerce Clause, the Supreme Court, and Public Health. Public Health Reports, 126(5), 750-753.
Legal Information Institute. (2020). Clause III: Power to Regulate Commerce. Retrieved from: https://www.law.cornell.edu/constitution-conan/article-1/section-8/clause-3