Here is the full list of all 28 1849 achievements.
The base game contains 18 achievements, and there is 1 DLC pack containing 10 achievements.
Complete the Dayton scenario in Nevada
Complete the Washoe City scenario in Nevada
Complete the Silver City scenario in Nevada
Complete the Gold Hill scenario in Nevada
Complete the Virginia City scenario in Nevada
Complete the Carson City scenario in Nevada
Complete the Virginia and Truckee Railroad
Build the Nevada State Capitol
Complete the Governor quest in Carson City
Complete the deep mine in Carson City