Alaska has a big vested interest in high oil and gas prices. Oil revenue accounts for 90% of the state’s tax haul. So its budget swells and oil royalties gush into a special state investment fund — the only one of its kind in the United States. And that can translate into windfalls for residents, who share in the oil bounty through annual dividends paid by the fund and, in boom times, direct payments from the state. For example, when oil and gas hit record highs in 2008, residents received $3,000 checks, twice what they normally get.