Proponents of an increase in Missouri’s gas tax, which goes to voters next month, are making their case around the state and picking up endorsements.

The gas tax, 17 cents a gallon, is the second lowest in the U.S. and hasn’t been raised since 1996. Proponents say inflation over the years means the buying power of 17 cents in 1996 is down to seven cents today, even though Missouri has one of the largest highway networks of any state in the country and has come close at times in recent years to being unable to find the money to fully match federal funds, which pay for work on interstates and big projects.

“So you can see we’re really upside down in funding our infrastructure,” Amy Jordan Wooden of safermo.com told Independence civic leaders this week.

The gas tax measure appears on the Nov. 6 ballot as Proposition D.

Here’s the math: The 10-cent-a-gallon increase would be phased in with two-and-a-half-cent increases for four years. Two and a half cents a gallon, officials estimate, costs the average MIssourian about $1.25 a month. At the full 10 cents, that’s an added $412 million for roads and bridges. The state gets 70 percent, or $288 million. The rest, $124 million, comes back to cities and counties.

“So again for communities this means a lot of money,” Wooden said.

In Independence, that would mean $1.84 million a year. The city has an estimated $1 billion in deferred maintenance overall, including roads and bridges.

“And this will really put a dent in that, towards chipping away at that,” City Manager Zach Walker said.

Proponents have made presentations to the boards of the Independence Chamber of Commerce and the Independence Economic Development Council, and those groups are expected to act on whether to endorse Prop D in the next few days.

Other cities:

• Blue Springs would get another $827,000 from the increase. The Blue Springs Chamber of Commerce has endorsed Prop D, calling the state’s transportation infrastructure “a grave concern for the state’s business community” and for safety, and saying poor roads are hurting economic development.

• Lee’s Summit would get $1.44 million. The Chamber of Commerce there has endorsed the increase.

• Grain Valley – $202,000.

• Buckner – $48,400.

• Oak Grove – $122,600.

• Sugar Creek – $52,600.

• Jackson County – $551,000.

Gov. Mike Parson has endorsed Prop D, as have the Greater Kansas City Chamber of Commerce, the Missouri Farm Bureau and the Missouri Chamber of Commerce.

On interstates and other major work, the federal government pays roughly $4 for every $1 in state money. The added revenues would give the state more flexibility should Congress come across with more money for roads and bridges.

“So what Prop D will do is have our match ready when the feds come a-calling,” Wooden said.