In the Republican stronghold of Atlantic County, N.J. (greater Atlantic City), a 32-year-old African-American woman with no campaign experience demolished a veteran, ultra-conservative Republican county commissioner.
Upsets were especially strong in neighboring Virginia, where a transgender toppled a 13-term right-wing legislative leader. A Peruvian immigrant trounced another conservative who had served 15 years in the House of Delegates. President Trump's candidate for governor lost by 9 percentage points.
Closer to home, Democrats won surprising, lopsided victories for mayor of Annapolis and mayor of Frederick.
Voters took out their anger toward Trump on anyone with an "R" next to his or her name.
This has to worry Republicans campaigning for the 2018 elections. It's a bad sign for the two Republicans running for Baltimore County executive, Al Redmer and Pat McDonough.
Turnout in this off-year election was surprisingly heavy, especially in Virginia.
National demographic trends already underway — rapid growth in minority voters and college-educated female voters and a decline in rural, conservative voters — may have been accelerated by Trump's antics in the White House.
How else can you explain the far-larger-than-expected turnout of millennials, Latinos, African Americans, gays, lesbians and college-educated women?
All these groups voted overwhelmingly for Democratic candidates and turned their backs on Republican politicians regardless of their record.
Moreover, Republicans failed to turn out their vote. Some have become disillusioned by Trump's crude language and negativity, his nasty comments and his tendency to blame other Republicans when things go wrong.
One political party suddenly has momentum; the other party is floundering.
Yet each election is different. This year's surprise Democratic wins don't guarantee success in 2018.
A divisive Democratic primary in Maryland could tear the party apart. Hogan could march into 2018 with a unified GOP and more than twice the campaign funds as his opponent.
For the moment, Democrats are giddy at their chances in 2018 and Republicans are alarmed. Will next year be a repeat of 2017? There's no way of ascertaining the answer to that question in advance.