Payoff for Valley Republicans about to arrive, via Highway 99 | Modesto Bee

U.S. Route 99, or just plain " 99" as it is known to locals up and down the Central Valley, is California's version of Route 66, the famous road that cut a swath through the American heartland and made its way into the culture and language of a generation.

Built in part along an old Indian migratory trail, Highway 99 was once the primary north-south route on the West Coast, at one point stretching from the Mexican border into Canada. In California, it was the road John Steinbeck made famous in Grapes of Wrath, his classic tale about the hard lives of the state's first migrant farm workers, Depression era refugees from the Dust Bowl.

In places the route passes through what are now major cities, including Sacramento, Modesto and Fresno. Elsewhere it still has the feel of an old country road. Drivers pass miles and miles of open farmland and orchards of peaches, plums and almonds. Barns that have seen better days dot the landscape on the other side of the shoulder.

The old highway could have died when fancy new Interstate 5 was built parallel to it on the other side of the valley. But instead of fading away the way Route 66 did when the interstates passed it by, 99 is fighting for its life. Already upgraded into a fully divided freeway along much of its path, the road is about to get its biggest-ever infusion of money and upgrades.

Proposition 1B, the $20 billion transportation bond California voters passed in November 2006, contained exactly one earmark setting aside some of its money for a specific project. That provision was a flat $1 billion for Highway 99.

The set-aside was the result of political demography and the law of numbers in the Legislature. It takes a two-thirds vote in the Assembly and Senate to put a bond measure on the ballot. And while Democrats hold commanding majorities in both houses, they didn't have enough votes to meet that higher threshold. They had to bring Republicans on board.

And as it turns out, while most Democrats in California live fairly near the coast, the Central Valley is filled with Republicans. So a big fix for Highway 99 was part of the price Republican lawmakers demanded for their support of the rest of the package. Democrats went along, and now the road that serves the nation's most fertile agricultural valley is about to get the benefit of that political bargain.

By the start of the next decade, after the engineers are done drawing the plans and the local transportation agencies assemble their matching funds, heavy equipment will be moving dirt and pouring concrete from one end of 99 to the other.

The bad news is that $1 billion does not go as far as it once did.

That still sounds like a lot of money to me. But it is enough to pay for only 13 projects to improve the road, with six of them slated for Sacramento or points north and the rest from Stockton south.

In Butte County, the state will add new lanes as the road passes through central Chico.

In Sutter County, the plan is to widen the road from four lanes to six and add a second bridge over the Feather River so that traffic there can cross on a divided highway.

In the Sacramento area, a traffic signal north of the city will be removed and replaced by an interchange, and south of town, the road will be widened to ease rush-hour traffic.

In the south, several more plans to widen the track from four lanes to six are on the drawing board for parts of San Joaquin, Merced, Fresno, Madera and Tulare counties.

All of this will put only a dent in the list of projects that regional transportation agencies have planned, which some local officials dream will one day make it into the interstate highway system. For the southern leg alone, from Kern County to Stockton, plans call for spending about $5 billion on improvements over the next 20 years. New, safer interchanges, stronger centerline medians and more rest stops are among the projects planned.

Traffic along that stretch, which now ranges from 42,000 trips a day near Interstate 5 in Kern County to more than 100,000 in Bakersfield, Fresno, Modesto and Stockton, is expected to more than double by 2025, with more than 250,000 motorists a day using the highway in those cities.

In between the towns, the road is clogged with trucks, some carrying local produce to the rest of the nation and beyond, others lugging goods from Southern California ports to the Central Valley.

Near I-5 in the south, trucks represent more than 25 percent of the traffic on Highway 99, compared with the statewide average of 9 percent.

The Proposition 1B money won't solve all of the problems on Highway 99. But this should be one case where voters won't have to wonder where their money is going. They will soon be seeing it just about everywhere they go on the east side of the Central Valley.

E-mail Weintraub at dweintraub@sacbee.com.