Dear Sonoma County Regional Parks Leadership and users of Sonoma County's parks,

If you have ever driven to one of our beautiful Sonoma County parks only to realize you left your annual pass in your other vehicle, I have a proposal for you.

A Revenue Opportunity: Offering a Discounted Second Vehicle Pass

As an annual pass holder and frequent visitor to Sonoma County’s regional parks, I am writing to propose a small but impactful addition to the annual pass program: offering a discounted second vehicle pass for $7.50 at the time a $69 annual pass is purchased. This add-on would appear only when a full-price $69 pass is already in the buyer’s cart and would not apply to the $49 senior discount pass. The research summarized below strongly suggests this change would generate meaningful new revenue at virtually no additional cost to the department.

The Problem: A Gap Between One Pass and Two

Many households own two vehicles. At $69 per pass, purchasing a second pass doubles the cost to $138, a price point that most families cannot justify when only one car visits the parks at a time. The result is predictable: families buy one pass, and when they accidentally drive the wrong car to the park, they either reluctantly pay the $8 day-use fee, park outside the park boundary and walk in, park inside and risk not paying, or simply skip the visit. In each of these scenarios, the county either collects less revenue than it could or loses the visit entirely.

This is not a hypothetical concern. A landmark study by the California Legislative Analyst’s Office (LAO) found that approximately two-thirds of all park visitors do not pay day-use fees. The LAO attributed this to visitors parking on nearby streets and walking in, or entering through unstaffed access points. This pattern of fee avoidance represents an enormous amount of uncaptured revenue statewide, and there is no reason to believe Sonoma County’s regional parks are immune to it.

Proven Precedent: States That Already Offer Second Vehicle Passes

Several state park systems have already implemented discounted additional vehicle pass programs and continue to offer them year after year, a strong signal that they are generating positive revenue:

• Wisconsin: Offers a reduced-rate additional vehicle pass at $15.50 (full-price pass is $28), available at checkout when purchasing a full-price 12-month pass. The second pass expires on the same date as the primary pass.
• Colorado: The “Aspen Leaf Multiple Pass” provides additional vehicle passes for households that already hold a primary Aspen Leaf Pass.
• Texas: Offers a secondary pass to a household member at the same address, limited to one secondary pass per primary pass holder.

These programs persist because they work. They convert households that would otherwise own a single pass into incremental revenue sources.

The Economics: Why Low-Cost Add-Ons Generate Outsized Revenue

A second vehicle pass costs the county almost nothing to produce; it is a printed hang tag. This makes it an ideal candidate for bundled add-on pricing, a strategy with robust support in economic research:

1. Bundling low-marginal-cost goods increases total revenue. Research from the Wharton School and MIT demonstrates that when the marginal cost of an additional unit is very low, bundling that unit at a discount captures consumer surplus that would otherwise be lost. A marginal-cost-to-price ratio well below 0.25 (as is the case here) signals especially strong bundling potential (Bakos & Brynjolfsson, MIT; Chu, Leslie & Sorensen, Wharton).
2. Low-cost add-ons at checkout have high conversion rates. E-commerce research consistently finds that add-on items priced at roughly 10–15% of the primary purchase convert at high rates because the buyer has already committed psychologically and financially. For a $69 pass, a $5–$10 add-on falls squarely in this range.
3. More accessible pricing captures otherwise-lost customers. For households that have never purchased a pass, the ability to split the value with a friend or family member (“We’ll each have a pass for $69 + $7.50”) lowers the psychological barrier to entry. The county collects $76.50 from a household that previously contributed nothing.

A Conservative Revenue Illustration

Suppose the county sells 5,000 annual passes per year. If just 20% of those buyers add a second pass at $7.50, that generates $7,500 in new annual revenue from existing customers alone, at near-zero incremental cost. If the add-on also encourages even a small number of new primary pass purchases (households that now see the combined value as worthwhile), the revenue gain grows further. And importantly, this revenue comes from people already at checkout, with no new marketing spend required.

Addressing the Concern: Could a Second Vehicle Pass Be “Abused”?

A reasonable question arises: could two friends split the cost of a primary pass and a second vehicle pass, each paying roughly $38 instead of $69? In theory, yes. In practice, this concern is far less significant than it appears, and even in a worst-case scenario, total revenue still grows. Consider three possible outcomes:

Scenario 1: Minimal abuse. Most buyers use the second pass for its intended purpose: a backup for their household’s second vehicle. The county collects $5–$10 in new revenue per add-on purchase, at near-zero cost. This is the most likely outcome, consistent with the experience of Wisconsin, Colorado, and Texas, all of which have offered discounted additional vehicle passes for years without discontinuing them.

Scenario 2: Some sharing, but net revenue still increases. Some friends split the cost. But consider what this actually means: two people who might have purchased one pass between them (or none at all) now contribute $76.50 combined. The county collects $7.50 more than it would have from a single pass purchase, and potentially $76.50 more than it would have collected from two people who previously walked into parks for free or parked outside to avoid fees.

Scenario 3: Widespread sharing, but top-line revenue still grows. Even in this unlikely extreme, top-line revenue increases. For sharing to actually cannibalize revenue, existing pass holders would need to coordinate in large numbers: one person buys the primary pass plus the add-on, and a friend who would have independently purchased their own $69 pass instead reimburses half of the cost. But this requires mass coordination that is practically implausible. Annual passes have rolling expiration dates throughout the year. If one person’s pass expires in January and a friend’s expires in July, splitting a single pass purchase means one of them pays for months of overlapping coverage they already have. The logistics simply do not favor it.

It is also worth placing this concern in context. The California LAO found that roughly two-thirds of park visitors do not pay day-use fees. Anyone can walk, bike, or be dropped off at most regional parks for free. The real revenue gap is not the hypothetical friend who splits a $76.50 pass purchase; it is the vast majority of visitors who contribute nothing. A second vehicle pass converts non-paying or under-paying visitors into paying ones. Worrying about pass sharing while two-thirds of visitors enter for free is, to put it plainly, solving the wrong problem.

Finally, the strongest empirical evidence against the abuse concern is that Wisconsin, Colorado, and Texas have offered discounted second-vehicle passes for years. If widespread sharing were cannibalizing their revenue, these programs would have been discontinued. They have not been. Instead, they continue to expand. These states have already run the experiment, and the results speak for themselves.

Recommendation

I respectfully urge Sonoma County Regional Parks to pilot a discounted second-vehicle pass, priced between $5 and $10, available as an add-on when purchasing a $69 annual pass. The implementation would be straightforward: the add-on appears in the online cart only when a full-price annual pass is present, limited to one add-on per transaction, and excluded from senior-discount purchases. A one-year pilot would provide clear data on uptake rates and revenue impact.

The evidence from other states, from economic research on bundling, and from the well-documented reality of fee avoidance at parks all point in the same direction: making it easier for pass holders to have a pass in every car will generate more revenue, not less. The current system leaves money on the table by pricing the second pass at a level few households are willing to pay.

Thank you for your consideration. I would welcome the opportunity to discuss this proposal further.

Sincerely,

Andrew Meyer
Sonoma County Resident and Annual Pass Holder

Sources

• California Legislative Analyst’s Office, “Improving State’s Approach to Park User Fees,” January 2017.
• Bakos, Y. & Brynjolfsson, E., “Bundling Information Goods: Pricing, Profits, and Efficiency,” MIT Center for Coordination Science, 1999.
• Chu, C.S., Leslie, P. & Sorensen, A., “A Simple Approach to Bundling Low-Marginal-Cost Goods,” Wharton School, University of Pennsylvania.
• Wisconsin Department of Natural Resources, “Vehicle Admission Passes,” dnr.wisconsin.gov/topic/parks/admission.
• Colorado Parks and Wildlife, “Parks Passes,” cpw.state.co.us/parks-passes.
• Texas Parks & Wildlife Department, “State Parks Pass Details,” tpwd.texas.gov.