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DENVER (KDVR) — Metro Denver is among the country’s areas with the most vaccination requirements, as the rest of the country slowly develops the kind of patchwork laws COVID has made all too familiar.

With the new FDA approval of the Pfizer vaccine, state and federal health officials are hoping for an uptick in vaccination rates. Across the U.S., states had already gotten the ball rolling to kick vaccinations into higher gear – first with carrots and now, increasingly, with sticks.

At least 15 U.S. states require vaccinations for some combination of state government workers, healthcare employees and/or education workers.

States with liberal governments tend to put vaccine mandates into play more often. About half the country has not made a state-level decision either way, but Democratic strongholds have come out early with requirements.

Colorado joins fellow blue states such as California, Washington, Oregon, Illinois and New York, among others.

Conservative states, meanwhile, have enacted laws that ban any kind of state-level vaccine mandate. Rocky Mountain neighbor Utah, along with Arizona, Arkansas, Florida, Georgia, Indiana, Montana, New Hampshire, North Dakota, Oklahoma, Tennessee and Texas have all banned state action.

Many of these bans, such as those in Indiana and Texas, also forbid local governments from requiring proof of vaccination.

Denver joins a host of cities with some kind of municipal or county vaccine mandate for some segment of workers.

Of the country’s 20 largest cities, more have mandates than not.

New York City, Los Angeles, Chicago, Houston, Philadelphia, California’s major cities and Denver top the list of vaccine requirement cities.

Cities in red states, such as Jacksonville, Phoenix, Charlotte, Indianapolis – hindered by state laws – do not.

City or state absence of vaccine mandates, of course, does not mean there are no private employers that require vaccinations for their workers.

Each of the states with bans on vaccine mandates have seen public protests against private employer vaccine mandates, including healthcare facilities and hospitality.

States with vaccine mandate bans have also seen local authorities pass their own mandates regardless. Dallas schools required vaccines in defiance of the state order.