In their important new book criticizing federalism, Malcolm Feeley and Edward Rubin argue that federalism (defined as constitutional guarantees for state autonomy) is unnecessary in the modern US in part because modern Americans no longer feel any major sense of identification with state governments. Feeley and Rubin concede that federalism might be a useful institution in societies where state boundaries coincide with major ethnic or religious divisions. For example, Canadian federalism allows the French-speaking minority to have an autonomous enclave in Quebec, where they can avoid domination by the English-speaking majority. French-speaking Quebecers identify with Quebec as much or more so than with the Canadian federal government. By contrast, Feeley and Rubin claim, most modern Americans identify as "Americans" first and foremost and have little or no loyalty to their states. I live in Virginia, but I feel no meaningful attachment to the state government in Richmond. My loyalty to the state of Massachusetts, where I grew up, is largely limited to rooting for Boston sports teams.
With a few exceptions such as Mormon identification with Utah and native Hawaiians' affiliation with Hawaii, Feeley and Rubin are largely correct in concluding that modern Americans feel little loyalty to their states. But they are wrong to claim that this undermines the case for federalism. Indeed, in one important respect it actually strengthens it. As I have discussed in various articles (e.g. here and here), one of the main benefits of federalism is interjurisdictional competition. States compete with each other to attract taxpaying workers and businesses; this competition gives them incentives to adopt good policies that will be appealing to the population, and also promotes desirable innovation in public policy. A state that makes a beneficial innovation will have a leg up on its competitors. The ability of citizens to "vote with their feet" is one of the main advantages of federalism. Obviously, foot voting is difficult or impossible in a situation where there is a unitary federal policy that applies to the whole country. In that situation, we can only vote with our feet by leaving the United States entirely.
As John McGinnis and I explained in this 2004 article, declining public identification with state governments actually increases the benefits of foot voting. A citizen who strongly identifies with Virginia might hesitate to leave even if another state is otherwise vastly more attractive due to its superior public policies. But a person who feels little or no loyalty to her state won't suffer from any such inhibitions. To the extent that modern Virginians are more willing to leave than those of 100 or 200 years ago, state governments elsewhere have stronger incentives to woo them, and Virginia's state government has stronger incentives to adopt good policies that will convince them to stay. Once we recognize the importance of voting with your feet as a major benefit of federalism, it turns out that declining loyalty to state governments actually strengthens the case for limiting the scope of federal power.