In at least one Season 1 episode and one Season 2 episode, the year was 1874. In Season 2, episode 19, "The Night of the Tartar," the time is identified as five years after the United States acquired Alaska, which was in 1867, making the year 1872. In Season 2, episode 21, "The Night of the Brain," the year is identified as 1872 in print, twice, meaning they have moved back two years in addition to skipping around a bit in between. In Season 2, episode 15, "The Night of the Lord of Limbo," it is only seven years after 1863, meaning 1870. Conclusion: not as bad as Daniel Boone, but certainly as bad as Little House on the Prairie, with moving back and forth in time.