What would happen to the US economy if the government abolished income tax?

Instant financial chaos and severe social and economic dislocation for a prolonged period of time. Decades, perhaps?

Without the means to pay the interest or capital on trillions of dollars of debt acquired by the governments, chiefly through the sale of bonds to US citizens and foreign investors, all government debt would instantly become worthless. Since a substantial amount of this debt is held outside the country, defaulting on it would produce rapid economic retaliation. US currency would collapse and become worthless to anyone holding it. All foreign trade would come to a standstill, because no one would sell to those holding US currency and the US would be unable to pay for any imports.

The economies of other nations would begin to destabilize: debt holders, trading partners, and those who are neither; all victims of a global economic disruption.

The effects would cascade rapidly through every segment of US society touched by the federal and state governments.