In 2015, then-Gov. Dannel P. Malloy and legislators agreed to dedicate a portion of the 6.35% sales tax — specifically one-half of 1 percentage point — to the state's Special Transportation Fund, which is funded by fuel tax revenues as well. The fund already had been receiving a small portion of sales tax receipts from car transactions.

By the time Lamont took office in 2019, that half-percent transfer was worth about $370 million. Arguing that wouldn’t be enough, the governor asked legislators to approve tolls: first in 2019 on all vehicles and one year later just on trucks.

After both failed, he convinced lawmakers to order the new highway mileage tax on most large commercial trucks.

But since then inflation has skyrocketed, taking sales tax receipts with it.

The $370 million transfer had nearly doubled by 2022. And nonpartisan analysts say it will pump $820 million into the STF this year and $875 million by 2026.

Read more: Even with gas tax holiday, CT’s transportation coffers are flush