From The Washington Post:

The 13 circuit courts are the second most powerful in the nation, serving as a last stop for appeals on lower court rulings, unless the case is taken up by the Supreme Court. So far, Trump has appointed 50 judges to circuit court benches. Comparatively, by this point in President Obama’s first term, he had confirmed 25. At the end of his eight years, he had appointed 55 circuit judges.

Trump’s appointments have flipped three circuit courts to majority GOP-appointed judges, including the U.S. Court of Appeals for the 2nd Circuit in New York. The president has also selected younger conservatives for these lifetime appointments, ensuring his impact is felt for many years.

The executor of this aggressive push is Senate Majority Leader Mitch McConnell (R-Ky.), who is almost singularly focused on reshaping the federal judiciary, twice ramming through Senate rule changes to speed up confirmations over Democrats’ objections.

“Leave no vacancy behind” is his mantra, McConnell has stated publicly. With a 53-to-47 Senate majority, he has been able to fill openings at breakneck speed.