In the Facebook group "The Murdoch Mysteries Appreciation Society", Pendrick Arrow gave me a handy guide to the timeline of 'The Murdoch Mysteries':
Season 1 begins in 1895 and each successive year, time progresses also by one year.
Season 1: 1895
Season 2: 1896
Season 3: 1897
Season 4: 1898
Season 5: 1899
Season 6: 1900
Season 7: 1901
Season 8: 1902
Season 9: 1903
Season 10: 1904
Season 11: 1905
For me, it's reminiscent of the basic timeline guide for 'Bonanza'. Each season of that Western was set 100 years previously. So the episodes from 1966 took place in 1866, 1971 episodes were set in 1871, etc.
But if you want to get more specific when thinking of both shows in the same universe, unfortunately their chronologies don't overlap. However, there would be a problem if the 'Murdoch Mysteries' wanted to get the world of 'Bonanza' up to Toronto - most of the cast is gone.
It would be great to imagine the two shows overlapping - if possible. But Erik "Hoss" Cartwright died in 1878; Little Joe died twenty years later. Their father, Ben, passed away in 1887, following the basics of the timeline and using the guideline of actors usually playing the same age as the characters they played. Oldest son Adam lived to 1910 (at least), but since Pernell Roberts has passed away, he's O'Bviously not available to play the role again even though Adam was around in 1905.
Candy Canaday is gone now as well, as is Hop Sing and Sheriff Coffee. Probably the only 'Bonanza' characters who could show up at Station #4 would be Griff King and Jamie Hunter Cartwright. And as old as the actors who played them - Tim Matheson and Mitch Vogel respectively.
It will never happen, of course. You can only get the fictional televersions of historical figures who appeared in 'Bonanza' into 'The Murdoch Mysteries' and even then you'd have to recast the role. When it comes to one such figure who did overlap - Mark Twain - the recasting should have been expected. After all, three different actors played Sam Clemens over the course of the 'Bonanza' run.
But wouldn't it have been fun to think of some kind of crossover for both series?