These 6 states might have been the targets of the Trump tax plan

President Trump and Republicans in Congress are working hard to turn their proposed tax reform framework into law. One controversial part of the current proposal involves ending the itemized deduction for state and local taxes. Although the provision applies to taxpayers across the nation, policymakers have pointed out that because of the differences in the ways that the 50 states raise tax revenue, taxpayers in certain states will on average see a bigger impact from the loss of the deduction.

As it happens, the following six states -- which represent the ones where taxpayers are able to deduct the largest percentage of their adjusted gross income -- have one thing in common: their electoral votes in the 2016 presidential election went to Trump's opponent. That has made some policymakers look more closely at the politics that might have been involved in adding this provision to the reform package.

6. Oregon

Oregon residents have an average adjusted gross income of almost $60,000, and 36% of the state's taxpayers itemize their deductions. On average, those who itemize their state and local taxes reduce their adjusted gross income by 7%, which is well above the national median level of 4.5%.

Oregon has one of the highest state income taxes in the U.S., with a top marginal tax rate of 9.9%. Although the state doesn't have a sales tax, it ranks near the middle of the country in terms of property taxes collected. Just 39% of voters cast their ballots for President Trump, compared with 50% for his Democratic rival.

5. Maryland

Maryland has a much higher adjusted gross income on average than Oregon, weighing in at about $72,750. That gives more than 45% of Maryland taxpayers the opportunity to itemize their tax deductions, and state and local taxes helped them reduce their income by 7.7%.

Maryland's tax system doesn't seem all that draconian on its face, with a top income tax rate of 5.75%. However, Maryland's counties impose their own income taxes as well, and all told, total state and local individual income tax collections per capita are the third-highest in the nation. Add to that a 6% sales tax and property taxes that are in the top third of states in the U.S., and you can see just how much Maryland residents get taxed at the local level. Trump lost Maryland 60% to 34%.

4. California

California is notorious for its high taxes, but its residents also enjoy a higher overall standard of living than much of the nation. Average adjusted gross income is almost $74,000. Just over a third of California taxpayers itemize deductions, and among those who do, state and local tax breaks give them a 7.9% reduction in their income.

California income tax rates are higher than anywhere else, with a maximum marginal rate of 13.3% on those with incomes of $1 million or more. Sales taxes of 7.25% are also at the top of the nation, and slightly more modest property taxes aren't nearly enough to take California off the list of heavily taxed states. In the 2016 election, President Trump got less than 32% of the vote, compared with almost 62% for his opponent.