WASHINGTON — The Supreme Court on Monday let stand appeals court rulings allowing same-sex marriage in five states, a major surprise that could signal the inevitability of the right of same-sex marriage nationwide.

The development cleared the way for same-sex marriages in Indiana, Oklahoma, Utah, Virginia and Wisconsin. Gay and lesbian couples started getting married in those states within hours.

The decision to let the appeals court rulings stand, which came without explanation in a series of brief orders, will have an enormous practical effect and may indicate a point of no return for the Supreme Court.

Most immediately, the Supreme Court’s move increased the number of states allowing same-sex marriage to 24, along with the District of Columbia, up from 19. Within weeks legal ripples from the decision could expand same-sex marriage to 30 states.