It is both, the Federal rate of 28% starts at 91k, but 25% starts at 31k. Since California starts their 9% tax at 51k I can change my comment to be that those making 51k get taxed at 41%. Even with a "progressive" tax system you are still paying more taxes then people assume.
I bring this whole thing up not because I don't understand marginal tax rates, but because the issue isn't "tax brackets" or marginal tax rates, but its deductions and other loopholes that allow people to pay far less then that in "effective tax rates". Lets not even get into the spending side of things and how much waste there is in the system that effectively funnels those funds to a federal contractors.
People have extremely naive perceptions of how taxes are used. It shocks me. The "throw tax money at it" attitude towards problems, especially in cities where people are reasonably wealthy, is very lazy.
This California tax predictor suggests a single person earning 51K will pay 40.65% marginal income tax rate, 22.5% effective income tax and only 29% effective including sales, fuel and property tax.
I sometimes wonder if it would substantially change the tax conversation if everyone understood what a marginal tax rate was.