It doesn’t take a rocket scientist to figure out that a co-headline tour featuring the two biggest heartthrob groups of the last twenty years will sell tickets. The real mystery is why no one thought to do this sooner. After all, each group has a loyal fan core that has stuck with their heroes since the early days. Putting both acts on the road in a tour affectionately called NKOTBSB should have happened years ago.

But 2011 is the year where it all happens. While the original list of shows resulted in sell-outs and additional nights in major markets, the new additions represent yet more markets for the NKOTBSB juggernaut.

The first new date is June 28 in San Antonio, Texas, at the AT&T Center. While San Antonio is squeezed in between previously announced Dallas (June 26) and Phoenix (June 30), the 15 other new shows mean the tour has been extended past its original July 9 stopping point well into the end of the month.

The first new date in this section of the routing – July 10 in Vancouver, B.C. – is actually the second night for that particular market. The additions also include Edmonton at Rexall Place July 12; the Calgary Stampede July 13; Minneapolis at the Target Center July 15; Kansas City at Sprint Center July 16; Tulsa at BOK Center July 17 and St. Louis at Scottrade Center July 19.

The remaining new stops are Louisville (July 20), Orlando (July 22), Greensboro, N.C. (July 23), Columbus, Ohio (July 24), Indianapolis (July 26), Cleveland (July 27), Atlantic City (July 29) and Hershey, Pa. (July 30).

Tickets for the new dates go on sale Jan. 15. For more info, click here for the NKOTBSB website.