Snowy owl occurrence in the United States was sporadically noted in historic newspapers. With the westward spread of settlement and development of towns and cities, there was also a greater geographic occurrence of sightings.
"A Snow Owl. A bird that deserves to be classed with the eagle, for size and strength, was killed on the bluff, last Wednesday, by our friend William S. Thompson, and by him brought into our office. From tip to tip of wings he measures for feet, and eight inches, and his tallons [sic] were like those of an eagle. They breed in, and usually frequent the northern regions, being numerous about Hudson's Bay and the Red River of the North." — from the Oquaka Spectator, as issued December 28, 1854 in the Jeffersonian 15(6): 2, published at Stroudsburg, Monroe County, Pennsylvania.
The "Oquawka Spectator" is apparently from Henderson County, Illinois, based upon an online search. The previous Wednesday correlates to December 20th, 1854.
Another potential instance is from Windham County, Vermont, as given in the community correspondence column.
"A Monster Owl. — Edward L. Prutt of Jacksonville shot an owl, on the 10th last, that measured 4 feet 9½ inches from tip to tip of his wings and weighed four pounds. His owlship had been making sad havoc in the poultry yard of J.B. Chase, killing one hen turkey that weighed 15 pounds, and nearly killing another about the same size. Although he was caught in a steel trap, but not liking such close quarters he flew with the trap which weighed 2½ pounds to the woods, about half a mile distant, where he was discovered and shot. We have only the weight and measurement to determine the species. If he was white he was probably of the species known to ornithologists as the strix nyctea, or snowy owl; if of a grayish brown color he belonged to the strix cinerea, or cinerous owl." — February 14, 1861 in the Vermont Phoenix 28(7): 2.
With this bird chasing after such large poultry, it was possibly some other species, as this prey would not conform with the small mammals typically eaten.
A report from California indicates the occurrence of an owl in Georgia.
"A fine specimen of the snowy owl was found lately near Macon, Ga., crippled by a shot. It is a far northern bird, and rarely seen in that latitude." — February 1, 1858 in the Additional Atlantic Items features, Daily Alta California 10(31): 1.
This report does however, say a while owl was going after poultry. Connecticut was the next state with a local newspaper report.
"H.P. Smith, of North Haven, Conn., recently killed a snow-white owl measuring five feet eight inches from tip to tip of his wings. The owl was pitching into the poultry, and Mr. Smith pitched into him with a pitchfork." — September 23, 1863 in the Daily National Republican 3(253): 2.
North Haven is in New Haven county.
One account from the southern plains is from Kansas.
"The Doniphan county Patriot says a Rocky Mountain owl was shot in that county by J.W. Starns, which was a snow-white bird, measuring five feet two inches from tip to tip. The owl was covered with heavy down from his beak to his toes. The eyes were large and lustrous, with yellow iris and dilated pupils. The beak short and curved, capable of inflicting a most formidable blow. The claws over an inch long, very much curved, and as sharp as thorns. This variety of owl is very scarce east of the Rocky mountains, and far surpasses in size, strength and beauty any of the owls in this country. — Possibly it was a wanderer from the Arctic regions." — January 30, 1864 in the Oskaloosa Independent 4(23): 2.
These two widespread record would seem to indicate an irruption of some extent, especially as they occurred during the same winter season.
It wasn't until 1871 that the next account was located.
"Mr. D.W. Reed, of Mecca, brought to our office, on Monday last, a bird rarely seen in this region, to wit: a Snow owl. Friday last it was seen to alight on a tree in Mr. Reed's door-yard, and was shot by his son. It is about two feet long and from tip to tip of wing about four and one-half feet. The general color is snowy white, with the upper part of head and back with lunated dark brown spots. This bird is only found in northern regions, and is certainly prepared from beak to claws for the severest winter weather. A peculiarity of this species of owl is that it hunts in the day time. It is said by naturalists to be of rapid and powerful flight, striking ducks, pigeons, &c., on the wing like a falcon, and seizes rabbits, squirrels and rats from the ground, and fish from the shallows." — December 6, 1871 in the Western Reserve Chronicle 56(19): 3 as issued at Warren, Ohio.
The general reference to "Friday last" might pertain to November 24th, which is the Friday prior to the Monday several days before the paper was issued.
Some of the items mentioned in this article are quite dubious, but at least it got some press and was therefore noted in the chronicles.
A next instance is from Tennessee.
"An owl, white as snow, with wings seven feet from tip to tip, was killed at Corinth a few days ago. It was driven from its native home, about the North Pole, by record tempests, which have swept over the country in all directions. The wings of the wonderful bird are preserved at the Scruggs House." — July 20, 1871 in the Memphis Daily Appeal 31(222): 3.
This is certainly an aberrant date, and it is not apparent how the bird would have survived from winter until summer?
A final newspaper article located is from the Pacific coast, in California.
"Our friend Jeff White has quite a curiosity at his place which he captured the other day. Upon getting into his orchard early one morning he discovered a large white owl perched in the top of a walnut tree. By a little ingenious maneuvering, some climbing and a few scratches he secured the bird and bore it in triumph to the house. It proves, upon examination, to be of a species known as the snowy owl (apis politis) and is very rare — for this latitude. Jeff has the bird securely boxed and tethered, and proposes to have it killed, stuffed and mounted as soon as he can find a taxidermist to do the work." — February 27, 1875 in the Los Angeles Daily Herald 3(129): 3.
These tidbits are a wonderful addition to the lore of this species, and are from newspapers, which are such an important source for the study of historic ornithology.
Each of these records indicate a time period when an irruption of this northern owl probably occurred. If these newspaper accounts were combined with a numerous other records, they would provide a much clearer indication of Snowy Owl occurrence in the lower 48 states prior to 1875.