The partisan divide between the Democrats and Republicans in the United States Congress is currently at an all time high. Partisan divides were lowest in the mid-20th century, but are higher now than they were in the late 19th century and early 20th century.
Posed less negatively, the Democratic and Republican party are more distinct than every before rather than being blurred by politicians who don't fit either party's mold, in part, due to "realignment" with one time Northeastern moderate Republicans now identifying as Democrats, and one time conservative Southern Democrats now identifying as Republicans in federal elections.
Deadlock isn't always a bad thing when the country is divided. A deadlocked nation may be one that shouldn't be making major changes from the status quo in the law. But, deep partisan divisions and divided government may make action entirely unachievable even on issues that necessarily call for some action to keep the institution of the federal government functioning, like the debt ceiling, appointments to bureaucratic posts, or approval of a federal budget.