The State of the Union is, well, unclear.

Adding to the unprecedented nature of the longest government shutdown on record, Speaker Nancy Pelosi again revoked her invitation for President Trump to deliver his annual address in the House chamber.

In a tit-for-tat exchange, Ms. Pelosi said Wednesday that she would not grant Mr. Trump access to address a joint session of Congress until the government had reopened. After suggesting that he would look for an alternative venue, the president said late Wednesday that he would delay his speech until after the federal government reopened.

Here’s what we know about the precedent for the State of the Union — and what could happen next.

Does there have to be a State of the Union?

Yes, according to the Constitution.

In outlining the framework for the executive branch, the founding fathers determined that the president “shall from time to time give to the Congress information of the State of the Union.”