U.K. Prime Minister Theresa May signed a letter this afternoon that officially declared the country's intention to leave the European Union. Addressed to European Council President Donald Tusk, it'll be hand delivered by Sir Tim Barrow, the British ambassador to the E.U., to Brussels tomorrow afternoon.

Boston is gearing up for a mass descent on drive thru lines: Google's Waze, the traffic navigation app, is teaming up with Dunkin' Donuts to order coffee for drivers before they arrive at brick and mortar stores, according to The Boston Globe.

If this goes well, Waze will expand the "order ahead" function to other merchants.

The partnership: Waze doesn't earn a commission on the Dunkin' Donuts sales, but Dunkin' Donuts is increasing the amount it spends on Waze ads. To place an order, users will need both the Waze and the Dunkin' Donuts apps installed and be registered with the Dunkin' loyalty program.

Why it matters: Brand loyalty for Dunkin' and Waze. Note, Starbucks had a similar partnership announced last week with Amazon's Alexa and Ford vehicles. The Dunkin' Donuts-Waze partnership allows anyone — not just Ford drivers with Alexa — to take advantage, but will bring people time and time again to both Waze and Dunkin'.

House Intelligence chairman Devin Nunes will not share the sources behind his claim that the Obama administration may have surveilled President Trump and/or his associates – even with his own committee.

Adam Schiff, the top Democrat on the committee, has already called on Nunes to recuse himself from the Russia investigation after it emerged that the chairman was on White House grounds when he reviewed the alleged evidence behind his claims. One House Republican, Walter Jones, echoed that call today.

Nunes is under increasing pressure, but made this defiant statement to a Fox News reporter today:

We will never reveal those sources and methods

During today's press briefing, Sean Spicer claimed that people would claim there was a Russia connection if Trump used Russian salad dressing, to which white house correspondant April Ryan began shaking her head. Spicer told her not to…

And Ryan tweeted in response:

Ryan then talked to CNN about the interaction:

Here is @AprilDRyan on air with me soon after the Russian salad dressing w @PressSec — her immediate reaction: https://t.co/0ryKeeXo8A 🥗
— Brooke Baldwin (@BrookeBCNN) March 28, 2017

Rural Americans would be most affected by Trump's proposal to pull funding from the Corporation for Public Broadcasting (CPB), the CEO Patricia de Stacy Harrison testified before a House Appropriations Subcommittee Tuesday. That's because more than 65% of the CPB's federal funding goes to keeping rural PBS and NPR stations running.

The rural-urban divide in public broadcasting: "Rural stations don't have a donor base," according to Harrison, and it already costs more to broadcast in rural areas, partly due to infrastructure upkeep.

Why it matters: Rural communities are the most at risk of losing public programming, and 62% of rural Americans voted for Trump. 70% of Americans oppose eliminating the CPB, according to a Quinnipiac poll.

Perspective: CPB gets about $500 million in federal funding annually. That's half of what Trump has requested this year to start the wall. Elmo should be safe, though, as Sesame Street has other funding sources.

House Republicans' decision to keep trying to repeal and replace Obamacare is not a good signal to insurers, who must decide soon whether or not to participate on exchanges in 2018. Whether or not Republicans are interested in stabilizing the marketplace will be key to their decision. Reopening repeal and replacement talks is not stabilizing, as it creates mass unpredictability about the future.

"If Republicans are clearly invested in your failure, as an insurer, you need to be concerned," said Rodney Whitlock, a former GOP Senate Finance Committee aide.

Our thought bubble (h/t Bob Herman): Insurers have just a couple months left before they file rates. And another game of patty cake in the House isn't going to make any insurer happy.

Fox News had the best quarter in cable news history, thanks in large part to its flagship program, The O'Reilly Factor, which had the biggest quarter ever for a cable news show (4 million viewers). MSNBC, CNN and Fox were all mostly up in daily audience and demo numbers. While MSNBC beat out CNN on the weekdays, thanks to record-breaking viewership of Rachel Maddow during the 9:00 p.m. hour, CNN still beat out MSNBC in viewership for the quarter.

Why it matters: Even though Fox pulled out the biggest overall numbers, MSNBC's growth from Q1 last year is notable. Per The Hollywood Reporter, MSNBC grew 55% and 61% in daytime and primetime, respectively, and 40% and 49% in the demo. CNN grew only 13% in daytime (+22% in the demo) but fell 17% in primetime (-11% in the demo). Fox's growth was in between with gains of 27% in daytime ratings (+32% in the demo) and 20% in primetime (+19% in the demo)

Why it doesn't matter: The fact that all three networks were up in total daily viewership means the Trump bump wasn't exclusive to the election. Per Pew, all three networks have experienced ratings bumps since 2015, meaning that cable news could be increasing in viewership more broadly.

Here's the map of the uninsured rates for counties throughout the United States for 2015, the second year when the Affordable Care Act was in full effect. The Census Bureau announced today that the uninsured rate dropped in 71.3 percent of the nation's counties between 2014 and 2015. Guessing we're going to hear about this in the next round of the repeal debate …

Data: U.S. Census Bureau Small Area Health Insurance Estimates; Map: Lazaro Gamio / Axios

Lt. Gen. Stephen Townsend, the commander of the United States-led international coalition against ISIS, said today that there was "a fair chance" that the U.S. had launched an airstrike in Mosul on March 17 that may have killed hundreds of Iraqi citizens, adding it was an "unintentional accident," per Defense One's Kevin Baron.

  • Estimates for death toll in the airstrike range from 80 to 511 with the likely number somewhere between 130 and 230. The Washington Post branded it "potentially one of the worst U.S.-led civilian bombings in 25 years."
  • President Trump's loosening of the rules of engagement in the region was "not really related" to the civilian deaths, according to Townsend.