The open platform car was leased (owned?) by the Detroit Photographic Company.

Responding to SouthBendModel34--The Chicago & North Western (C&NW)line through Lewiston I believe started life as the Winona & St. Peter Railroad which had a close association with the C&NW. Note the C&NW logo on the front of the smoke box of number 148. Construction was started about 1866 and the C&NW purchased the railroad in about 1867 though it operated it as a separate entity until 1900. The railroads shared motive power designs and classification codes though motive power , numbering and logos on locomotives were kept separate until the final merger.

The cave on the right is a legend about it being the Devil's Hole. (see photo)

[The photo you attached related to the Lewiston in New York state, not Minnesota. -tterrace]

[Thanks. Being a Brit, I don't know my NY from my MN...]

The number plate at the center of the locomotive smokebox seems to read 118.

The line through Lewiston MN is currently the Dakota, Minnesota & Eastern, which is a successor to the Chicago and Northwestern Railway. (Which may or may not have constructed this line: can any Shorpy Sleuth come up with a construction date for the RR through Lewiston MN?

The trestle fill-in would probably be not too long after the opening of the line.

Can photo enhancement read a RR name on the side of the tender, or the name of the single passenger car? (Which is probably the RR's Business Car. This looks like an inspection trip to check on the progress of the trestle fill.)

There's curved, raised lettering on the locomotive smokebox which I would guess to be the name of the locomotive. builder. Can that be enhanced ?

[Signs on the tender and car aren't legible. -tterrace]

The engine is a Chicago & North Western S-2 class 4-6-0 built in 1890. As such it was an example of the biggest and best the railroad had before 1900. The engine lasted until 1925 when it was scrapped. In this photo it hauls one passenger car--an attendant appears looking out from behind the car suggesting a very special train. Perhaps top management. Perhaps an inspection train. The locomotive is a good deal more powerful than needed for one passenger car--an ornate at that.

It was common practice when these rail lines were built to erect trestles over low places and when the line was completed and in service go back and fill in around the trestle. This is a good picture of that being done.

I'd like to have a look in that cave on the right.
Does anyone know if the Pulpit still exists?

That locomotive is equipped with a primitive Link and Pin coupler. You can see a link hanging from the pin, plain as can be. This is a dangerous manual coupling system that exposed RR workers to dismemberment and death.

There is no air brake hose visible, either.

The 1893 railroad safety appliance act made automatic couplers and air brakes mandatory. It was phased in over seven years, so the actual date of the photo is most likely before 1899 and certainly is not after 1900.