The U.S. Senate has voted to fund the federal government through September of next year, the final legislative action needed to avoid a threatened partial government shutdown.

The congressional upper chamber also voted to extend a cut in taxes that fund Social Security, a federal program that provides income to retirees.

For most of the year, U.S. lawmakers follow political, and often partisan, imperatives when conducting the nation’s business.

But in late December, a different imperative emerges: a desire to wrap up legislation so that lawmakers can get home ahead of the Christmas and New Year holidays. The end result is sudden and swift compromise, producing last-minute bills that get voted on with a minimum of debate, often before lawmakers even have a chance to fully read the legislation.