Parkston drivers: SD gas and diesel averages tick higher on 7/21/26

Parkston-area drivers got another small lift in fuel prices in South Dakota’s latest AAA average check. AAA’s South Dakota regular gas average is $3.9210 as of 7/21/26—up from $3.8720 yesterday. AAA’s diesel average is $4.7230 as of 7/21/26—up from $4.6250 yesterday.

Regular gas: AAA SD average is higher across most checkpoints

South Dakota regular (Price as of 7/21/26): $3.9210

• Yesterday: $3.8720
• Week ago: $3.6970
• Month ago: $3.8490
• Year ago: $2.9780

For commuters and families, higher regular-gas averages typically mean fewer “easy wins” when planning errands or weekend travel—especially if prices stay firm compared with last month and last year.

Diesel: higher averages keep operating costs under pressure

South Dakota diesel (Price as of 7/21/26): $4.7230

• Yesterday: $4.6250
• Week ago: $4.3280
• Month ago: $4.5050
• Year ago: $3.3480

Diesel moves can matter fast for delivery routes, construction fleets, service technicians, and farm/ranch operations—where fuel cost is part of the daily math behind bids, schedules, and operating budgets.

National context: EIA’s latest weekly on-highway averages moved up too

Looking beyond South Dakota, EIA’s Gasoline and Diesel Fuel Update for the week ended 7/13/26 put U.S. on-highway regular gasoline at $3.855 (up from $3.777 the prior week) and on-highway diesel at $4.796 (up from $4.578). That same up direction is consistent with what AAA is showing for South Dakota’s statewide averages.

What to watch next—and how to compare locally

AAA is tracking South Dakota statewide averages, which are a useful benchmark for Parkston-area planning—but individual station prices in and around Parkston can run higher or lower.

Local contractors and public works staff may also watch South Dakota’s Fuel Price Index, which is based on wholesale terminal inputs and uses four-week averages (not the same thing as pump-price averages).

If you’re shopping around, it can help to compare a few nearby stations using the latest listings.

Community question: What’s the highest and lowest pump price you’re seeing locally right now?

Sources

• AAA South Dakota average gas prices (regular & diesel) — daily table (Price as of 7/21/26)
• EIA Gasoline and Diesel Fuel Update — U.S. on-highway retail series (latest weekly values)
• South Dakota DOT Fuel Price Index (wholesale terminal inputs; four-week averages)
• City of Parkston business directory — gas stations / fuel oil & propane list