Sam Smith performs on the BBC Radio 1 stage at T in The Park

Sam Smith performs on the BBC Radio 1 stage at T in The Park on July 13, 2014 in Kinross, Scotland.

Ollie Millington/WireImage
There's a new British invasion on the Hot 100.

And, an Australian Invasion. A Canadian, Norwegian and Scottish one, too.

The upper ranks of the Hot 100 of late have belonged to acts from outside the U.S., from Canada (MAGIC!'s "Rude") and Australia (Iggy Azalea's "Fancy," Sia's "Chandelier") to England (Sam Smith's "Stay With Me," Disclosure's "Latch," featuring Smith), Norway (Nico & Vinz's "Am I Wrong") and Scotland (Calvin Harris' "Summer").
 
The influx of foreign talent follows breakthroughs by Lorde (New Zealand) last year, Gotye (Belgium) in 2012 and Adele (England) in 2011.
 
Meanwhile, Australia's 5 Seconds of Summer just blasted onto the Billboard 200 at No. 1 with a hefty 259,000 first-week copies sold of their debut album, according to Nielsen SoundScan (and join English/Irish quintet One Direction in the battle for boy-band supremacy, both in the U.S. and worldwide).

Gotye Wants 'State of the Art' To Be His Next U.S. Single

Gotye Wants 'State of the Art' To Be His Next U.S. Single

Such non-domestic chart dominance stands in stark contrast to a year ago. By the numbers: seven of the lead acts in the Aug. 9, 2014 Hot 100's top 10 are foreign. A year ago, only 2.5 were. (Why a .5? Robin Thicke was born in Los Angeles but has dual American/Canadian citizenship.)
 
Five years ago (on the Aug. 8, 2009 Hot 100), the gap was even greater, as just one non-American-born act populated the top 10: Canada's Drake. (Also in that top 10: Sean Kingston. Although born in Miami, he moved to his namesake Kingston, Jamaica as a child.)
 
In a roundtable discussion (via email) with U.S. record label executives and radio programmers, certain factors pinpoint why the Hot 100 has become the domain of acts from other countries.

Let's look at three key reasons why.

WHERE THE HITS ARE

Most simply, songs that react the best among audiences will always find their way onto playlists. Right now, the biggest hits happen to come from acts beyond U.S. borders.
 
"Great songs win," says Erik Bradley, assistant program director/music director at CBS Radio's top 40 WBBM Chicago. "And, all these hits -- 'Rude,' 'Fancy,' [British-born] Charli XCX's 'Boom Clap' -- are incredible songs."

Charli XCX performs in 2014

Charli XCX performs at the Sonos And Pandora Present "An Evening With Charli XCX" event at Sonos Studio on June 10, 2014 in Los Angeles, California.  Joe Scarnici/Getty Images for Sonos

Going hand-in-hand with what infuses top 40 playlists, since its inception more than a half-century ago, the format has prided itself on breaking new music, often from new artists. In summer 2014, the biggest new hits belong not only to artists, but rookies, especially, hailing from outside the country.
 
"Discovering new artists is one of the many things that keeps radio great," says Tommy Chuck, program director of Clear Channel Media and Entertainment-owned top 40 WFLZ Tampa, Fla.
 
"Azalea and Smith were chosen as Clear Channel [multi-platform new artist exposure program] 'On the Verge' artists months ago. We're proud to have championed them."

LACK OF HIT U.S. PRODUCT

Meanwhile, the bevy of foreign-born hits coincides with a relative lull in releases from American top 40 standbys.
 
"A lack of core artists can make room for new artists," notes Jeremy Rice, PD of Cox top 40 WBLI Long Island, N.Y. "Rihanna is in between albums rights now. So is Bruno Mars. Lady Gaga is not as hot as she was. And, Beyonce, as huge as she is, is not having huge top 40 hits from her latest album."
 
"This opens up the chart, and I think it's great," Rice says. "Right now, Sam Smith has the best shot of becoming a core artist and we always need new core artists."

YOUTUBE, SOCIAL MEDIA & TECHNOLOGY

By far, the biggest reason cited for the current wave of worldwide hits working in the U.S. is technology. The way we now consume music, industry insiders say, is clearly the main catalyst.
 
Prior eras have brought foreign acts to U.S. shores (and airwaves), most famously starting with Beatlemania 50 years ago. A second British invasion followed in the '80s, led by new wave/pop acts. (The Beatles were simply an unstoppable force whose U.S. success was inevitable; two decades later, such U.K. acts as Duran Duran, Culture Club and Wham! helped American music fans transition from the disco-dominant '70s.)

Boy George Performs in London

April 3: Boy George performs on stage at Indigo2 at O2 Arena on in London, England.Gus Stewart/WireImage

Now, the reach of YouTube and social media are shaping sounds like never before.
 
Says Def Jam executive vp of promotion Rick Sackheim, "America's consumption of music, especially new, cutting-edge artists and songs, has never been stronger. Everyone wants to 'discover' the next 'cool' thing. Foreign acts have always crossed into American culture once their fame gets to the point that they become undeniable. The difference today is that music discovery no longer takes months. Now, it can literally take minutes.
 
"Artists like [Def Jam's Azalea] have built up fan bases by releasing music and dropping videos and other clips on their social media sites," Sackheim says.
 
"I think labels have become better at the overall set-up of music from outside the U.S.," adds RCA executive vp Joe Riccitelli. "A constant flow of new [social media] content really helps stoke the fires."
 
Technology may not be aiding only audiences. Artists themselves benefit from modern tools, and no longer need to be near music meccas to produce hit songs, posits Interscope senior VP of promotion Chris Lopes. "Access to laptops and new software levels the playing field for talented artists everywhere to record quality music."

Disclosure backstage at Coachella 2014

Disclosure backstage at Coachella 2014 on April 13, 2014.Misha Vladimirskiy

Ultimately, says Lopes, labels have better access to acts abroad, which has changed their A&R practices. "Music is shared and discovered differently now. It crosses borders and boundaries faster and more easily. As a result, fans hear new music immediately, labels cast a wider net to scour for talent and radio is more open to more kinds of music, like house from Disclosure."
 
"We've had success with international artists for as long as I've been at Interscope, 16 years, but music is clearly weighted more toward foreign hits now," Lopes says. "For us, in the last couple years, Carly Rae Jepsen's 'Call Me Maybe' blew up in the U.S. after it was a hit in Canada, driven by YouTube views and Justin Bieber's social media push.
 
"Now, 'Latch' is a U.S. hit, but it had 25 million [YouTube] views before we impacted radio. Top 40's audience was more familiar and passionate about the song than many radio programmers initially realized."
 
It's fitting, then, that even one of the biggest current hits by an American act, Maroon 5, is called … "Maps."
 
"The digital age has changed our mindsets, Rice says. "Australia" -- and England, Norway, Scotland and other foreign countries -- "isn't really that far away anymore."

A version of this article first appeared in the August 16th issue of Billboard Magazine