Sooner rather than later, the legislature will need to address how to finance transportation – both highways and transit. This has been an ongoing and highly politicized discussion that appears unlikely to have an easy resolution as long as Minnesota has divided government. At the core of the problem with highway finance, in my view, is the basic structure of the gas tax – a fixed dollar amount per gallon of motor fuel – whose revenue yield has been eroded by inflation as a result.
The gas tax has been the centerpiece of Minnesota highway finance for nearly a century. But the tax’s structure requires ongoing legislative maintenance – regular adjustment of the rate to offset the effects of price inflation. Political polarization and/or changing political values (by Republicans mainly) have effectively made that difficult, if not impossible, for the last two to three decades. In my view, that state of affairs has largely creating the highway funding crisis in which the state is mired.
The gas tax equals a fixed dollar amount (currently, 28.5 cents) per gallon. What that means is that as prices increase with inflation, the real rate of the tax declines. Inflation provides an automatic tax cut, which also reduces the revenues for constructing, reconstructing, and maintaining highways. (The constitution has an ironclad requirement to use gas tax revenues only for highways and roads.) Policymakers and the media wring their hands over the effects of more fuel efficient vehicles and electric vehicles as causing a problem, since these vehicles use less or no taxable gasoline or diesel fuel. (EVs are a minuscule percentage (<1% of new sales!) of the fleet using highways. That will change but it will likely take a very long time.) But that effect pales relative to the impact of inflation and the failure of the legislature to regularly increase the tax to keep pace.
The table below shows how inflation has affected gas tax rates over time. The gas tax was enacted in 1925 at a rate of 2 cents/gallon. The legislature has increased the tax rate 12 times since, most recently in 2008. The table shows what the rate would have been in each year of rate increase in 2019 dollars (adjustment was made using the consumer price index) and how much the tax was as a percentage of the retail price of gasoline. That approach (imposing the tax as a percentage of the sale price) would avoid the need to adjust the rate, because it would go up or down with the price of the gas (or diesel fuel); that is why it is unnecessary to index the sales tax.
| Year of rate increase | Tax rate when enacted | Tax rate in 2019 dollars | Enacted rate as % of price |
| 1925 | $0.02 | $0.29 | 9.1% |
| 1929 | 0.03 | 0.45 | 14.3% |
| 1941 | 0.04 | 0.70 | 21.1% |
| 1949 | 0.05 | 0.54 | 18.5% |
| 1963 | 0.06 | 0.50 | 19.4% |
| 1967 | 0.07 | 0.54 | 21.9% |
| 1975 | 0.09 | 0.43 | 17.0% |
| 1980 | 0.11 | 0.34 | 12.8% |
| 1981 | 0.13 | 0.37 | 10.9% |
| 1983 | 0.16 | 0.41 | 13.1% |
| 1984 | 0.17 | 0.42 | 14.7% |
| 1988 | 0.20 | 0.43 | 22.2% |
| 2008 | 0.29 | 0.34 | 8.7% |
| 2019 | 0.29 | 12.1% | |
| Average | 0.44 | 13.3% |
The current tax rate (28.5 cents) equals the original tax rate enacted in 1925 updated to 2019 dollars. If the tax rate were simply the average of the rates enacted by 13 legislatures (44 cents in 2019 $), that would go a long way to providing adequate highway financing. It would be 15.5-cent (or a 50%) increase in the rate compared to present law. Governor Walz proposed a 20 cent increase, phased in, but much of that was required to make up the deficiencies caused by the long running failure of the legislature to keep updating the tax rate for the effects of price inflation. Had the rate regularly been adjusted since 1988 (keeping it at about 43 cents) that probably would have been unnecessary.
Had the tax – like a standard retail sales tax – been imposed as a percentage of the retail price, the picture would have been somewhat less rosy. The tax now is about 12% of the price, which is only a little less than the average (13%) over the period. Note that this approach would impose a stiffer tax on diesel fuel purchases, since the price of diesel fuel is higher than for gasoline. That probably would be justified, since diesel fuel contains more energy and because it is predominantly used by heavier vehicles (trucks, buses, and so forth) that do more damage to roads and highways. That would be consistent with a user fee model of the tax, which it roughly is. A percentage tax would provide a more volatile and less reliable source of revenue. See the graph in this blog post from the US Department of Energy that shows a 75-year history of retail gasoline prices to get an impression of that volatility. A tax based on price would also be less well aligned with a user fee model of the tax, since the burden of the tax would vary quite a bit over time based on world oil prices, rather than following use of roads and highways.
My observations:
- To help put the effects into context, I did some back-of-the-envelop calculations. If the 1988 tax increase had been indexed to CPI inflation (and skipping the 2008 increase as unnecessary), my rough calculations show the state’s highway user trust fund would have collected about $6.5 billion more in revenue between fiscal years 1990 and 2019. That is about a one-third increase in actual collections, which were about $20.4 billion over that period. Under the constitution, that money would have funded state trunk highway costs, as well as aid payments to counties and cities. That likely would have come close to meeting much of the highway funding needs, as well as holding down property taxes which are increasingly paying for local streets and roads.
- My adjustments are based on the CPI for all urban consumers. One could make a case for indexing to the cost of highway construction and maintenance. That would be more consistent with an underlying theory that the tax is a user fee, since it would be adjusted by the changes in the price of user costs. I believe that is the method used by some states with inflation-adjusted gas taxes.
- The current political environment – at least since the advent of Grover Norquist and no-new-taxes Republican theology in the late 1980s – has been lethal for the efficacy of fixed dollar excise taxes as a revenue source. The biggest casualty is the gas tax and highway finance, but Minnesota’s alcohol excise tax is another victim. It is structured in the same way as the gas tax ($ per volume) and its rates were last increased in 1987. Fortunately, it is a minor general revenue source, but the social costs of alcohol abuse and their burden on the state budget are immense. Substantially increasing the excise tax rates based on those costs could easily be justified.
- The no new taxes theology has not, however, prevented some very large increases in cigarette and tobacco excise taxes, and not only when the entire government is controlled by Democrats. (Governor Pawlenty’s cigarette “fee” is Minnesota’s notable exception.) That is explained (probably) by the now very small percentage of the population that smokes and that most of them want to quit.
- Minnesota Republicans have idiosyncratic views on inflation indexing and taxes – views that would get an F from a neutral logic or economics grader but an A from a proponent of minimizing the size of government. Early in my career as a legislative staffer, a Republican signature issue was to index the income tax to prevent inflation from driving taxpayers into higher tax brackets and eroding the value of fixed dollar deductions and personal allowances. That was a central focus of the campaign that elected Al Quie as governor and yielded a 33-seat Republican pickup in the House in 1978. The 1979 tax bill indexed income tax brackets, the standard deduction, and personal credits for inflation, preventing inflation from imposing “unlegislated tax increases.” The federal government followed suit in 1981 and both taxes have retained core indexing provisions ever since (despite extensive opposition and complaining by DFLers about the effects on state revenues in the early 1980s). But when the cigarette excise tax rate was indexed in 2013 to maintain the integrity of the dollar value of its rate, that was a tax increase on “auto-pilot” according to Senate Republicans, which they repealed as soon as they could (2017 bill that then Governor Dayton signed under protest). Their views on indexing policy are as inconsistent with basic economic principles (premise: neutralize inflation’s effect on the tax’s dollar values) as they are consistent with their political principles (premise: reduce taxes any way you can).
- I’ll write separate posts on (1) the merits of user funding for highways and (2) why there is already extensive general revenue funding of highways in Minnesota, despite the contrary perception.
- The federal gas tax has exactly the same flaw. The gridlock and GOP tax aversion has prevented an increase in its rate since 1993. One obscure Democratic presidential candidate (Congressman Delany) has proposed fixing this, as I noted here. Fat chance for either his candidacy or the proposal.