New Year’s Eve and Day did not prompt much celebration among missionaries in the Southwestern States Mission. The end of the calendar year did, however, inspire a degree of introspection, some resolutions, and many reports for office missionaries to write.
I find two mentions of non-missionaries celebrating New Year’s: “the booming of cannon and blowing of whistles” and a “New Year’s dinner.”  The only instance of missionaries explicitly commemorating comes, probably intended ironically, from Elder Brooks: “Elder Jensen and I helped Bro. Thorne kill hogs. That was a New Year celebration.” 
The change from the Nineteenth to the Twentieth Century generated “a great discussion in the papers and by leading educators over the question, ‘When does the twentieth century begin.’ Some claiming Jan. 1st 1900, some claiming that the 20th century does not begin until Jan 1st 1901.”  Elder Jones, without explanation, noted the passing of “the old century” in both 1899 and 1900.” 
I have not noticed fin de siècle enthusiasm in the diaries except that on the first day of the Twentieth Century President Duffin predicted the return of the Savior.  In other years Duffin made more modest statements.  One year his Christmas entry was more “resolute” than his New Year’s entry.  Sister Cluff also made a New-Year’s-like entry at Christmas. 
With the usual caveats about sample size… the two missionaries that pay the most attention to the New Year, Duffin and Cluff, were twenty years older than the other missionaries and they worked in cities. Cluff mentioned “dense throngs” of people “on the streets” on Dec 30 and 31.  Like Duffin, her New Year’s Day entry includes resolutions of faithfulness. 
The mission produced annual reports in December / January for the Historian’s Office and the Presiding Bishop. The reports include dozens of calculations and seem to have taken significant effort; sometimes Duffin does not note their completion until the end of January. 
The “Southwestern States Mission” series (homepage) examines mission life in (mostly) Texas around 1900.
 Sister Cluff in St Louis in 1904 also noted an increase in pedestrian traffic in the lead-up to the new year (the diary entries are quoted in a subsequent footnote). “Last night we could hear the booming of cannon and blowing of whistles at the city of Dallas, ten miles away, announcing that 1899 was going out and 1900 coming in.” (Duffin, 1900 Jan 01 Mon); “The women folks had gone over to a neighbor’s to eat New Year’s dinner.” (Jones, 1902 Jan 01 Wed).
 Brooks, 1901 Jan 01 Tue. Elder Brooks was working without a companion as conference secretary; Elder Shipp and Elder Jensen had come to visit for a few days, possibly on account of the holidays. Hog hunting and butchering were a winter chore that sometimes overlapped the holiday. Brooks’s description of butchery as celebration is, I think, intended a touch ironically. That is, I think Brooks enjoyed the activity but did not think of it as an intentional celebration comparable to firing guns at midnight on New Year’s Day. There are instances of hog killing on Dec 19, 29, 30; Jan 19; Feb 04, and 26; from Forsha, Folkman, Brooks, and Jones.
 Duffin, 1900 Jan 02 Tue.
 “The last night in the old century.” (Jones, 1899 Dec 31 Sun); “The last year of the old century went out & the last day was very cold.” (Jones, 1900 Dec 31 Mon); “When we arose the weather had not moderated any; the new year came in a-roaring.” (Jones, 1901 Jan 01 Tue).
 “At the beginning of this, the first year of the twentieth century, I dedicate myself and all that I possess to the service of the Lord, and it is my most earnest prayer that my family and myself may never waver in our devotion to the work of the Lord which He has established in this dispensation for the salvation of His children. I know there are trying times before us, but I also know, if we will be faithful there is a crown of righteousness prepared for us in the Father’s kingdom. The century just closed has been one filled with marvelous events. Many discoveries and inventions for the good of mankind have been made, but the events, the effects of which will be the most far-reaching have been in the religious world. God and His Son Jesus Christ came to earth, heavenly beings again began to minister to man, the priesthood and the gospel were restored and the final work of reclaiming the world from the grasp of Satan was commenced. The coming century is full of promise to the saints. During this century they will return to the lands from which they were driven by mob violence, the city and temple in Zion will be built, and the glory of the Lord be there, and the Saviour administer personally among his people upon the earth. Great changes will take place among the governments of the world; there will be wars and bloodshed, famines and pestilence, destructions by sea and by land, earthquakes in various places, and the hearts of men failing them for fear. I wish here to caution my children : When you see these judgments poured out upon the wicked, doubt not the mercies of God. Often He destroys in the flesh that He may save the spirit. During the last year, my work, to me, has been one of pleasure and profit. Trials there have been some, but they have but caused me to more fully sense my weakness, and taught me to put my trust in my Father in Heaven.” (Duffin, 1901 Jan 1 Tue).
 No statement: 1900, 1903. “We begin our work in the mission under most favorable conditions. Our finances are in good order, the Elders are united and earnest and there is but little persecution that follows the Elders work. It is our desire to see the work of our Father advanced in the mission during the coming year, and many souls be brought to a knowledge of the truth and be adopted into His kingdom.” (Duffin, 1902 Jan 31 Fri); “This morning at ten o’clock I arrived in Kansas City again from my house in Utah. While it is a pleasure to visit my loved ones and to be with them, yet I am always pleased to get back to the mission for this is where the Lord has appointed me to labor. It is my desire that I and my family will ever place first our duty and not our personal pleasures and desires.” (Duffin, 1904 Jan 1 Fri). “At the beginning of the new year, I feel very grateful to my Father in heaven for the many blessings my family and self have enjoyed during the past year; also for the blessings He has so abundantly bestowed upon my brethren and sisters in the mission where I am presiding.” (Duffin, 1906 Jan 1 Mon).
 “Six years ago to-day I spent in Dallas Co Texas washing my clothes. To-day I am spending it with those whom the Lord has given me. The first visit I have had with them for six months. It is my desire to serve the Lord all the days of my life, to be true to all of my family and to the servants of the Lord and His holy laws. It is my prayer that all of my family may have the same desires and will never waver in their devotion to that which God has revealed from heaven. Opposition will come from both members and non-members of the church, but those of my family who will be true to God and his holy purposes will rise above all who seek to destroy them and will be honored in the kingdom of God, and some of them will be called to preside in important positions in the church of our Lord.” (Duffin, 1905 Dec 25 Mon). Duffin’s use of “those whom the Lord has given me,” “Holy laws,” and “opposition” should probably all be read in the context of Duffin’s post-Manifesto polygamy (and this post was written while Duffin was visiting his second family).
 “Christmas day – The first in my life to spend away from my darling children. I hope they are happy today. When I rose this morning my first thoughts and prayers were for them, that in the coming year they might be blessed, prosper, and progress in the work of the Lord. That they might more fully understand and comprehend the necessity of living more correct lives. I will not think of home today more than I can possibly help for fear I lose control of my feelings. … Our guests remained for the evening and departed at a late hour, each wondering where we would be next Christmas. … So ends my St. Louis Christmas. So much in my life has been revolutionized in the last year. After a calm, even [illegible] of fourteen years that I shall not even try to imagine where of what I shall be in one year from this time. But whatever comes, I hope I may be able to stand firm and steadfast in the faith.” (Cluff, 1904 Dec 25 Sun).
 “The old year is drawing to a close, but few more days are left.” (Cluff, 1904 Dec 29 Thu); “This morning I went down town to do a little shopping. One would [illegible] to see the number of people on the streets that this holiday [illegible] just coming on. Dense throngs at the crossings and it requires a policeman to keep the people from being run over by cars and vehicles of all descriptions.” (Cluff, 1904 Dec 30 Fri); “The last day of the old year and tomorrow ushers in another year book of life whose pages I trust, mine at least – will be without blemish at the end. It is so easy to make good resolutions but sometimes hard to keep them. We need not unless we seek at the right fountain. A beautiful passage comes to mind in John: 4, that “whoso drinketh of the water that I shall give him shall never thirst. But the water that I shall give him shall be in him a well of water springing up into everlasting life.” What a beautiful promise to us, the children of God, but few seem to seek often those blessings and promises. This afternoon I went down town to get my photos, they not being finished. I went to see the celebrated actress Ada R[illegible] in “The Taming of a Shrew.” She is inimitable in that character and her support, Mr. Richmond is simply splendid. I walked down Olive Street a ways wondering what so many people could find on the street to be crossing and re-crossing, then happened to think it is New’s Year’s eve, when such crowd might be expected on the streets. … These are the last words I shall write in my book this year. Good bye old year. You have brought me many pleasure as well as pain.” (Cluff, 1904 Dec 31 Sat).
 “May the few remaining pages of my life be without spot of blemish, just as I now write this clean white page. May I through my faithfulness enter into His rest when my time in mortality is done.” After quoting some poetry and describing the day, the entry ends: “So ends the first day of the New Year. May every one be as peaceful and [illegible] and happy as this one and I hope to realize every desire of my heart in righteousness before the Lord.” (Cluff, 1905 Jan 01 Sun).
 In the entries for 1901 Dec 31 Tue and 1902 Jan 1 Wed, Duffin seems to reproduce the entirety of the 1901 report with dozens of entries. The other years were finished later in January. “…I also had to begin the work of getting up our yearly tithing and other reports…. The census reports are not all yet in.” (Duffin, 1904 Jan 1 Fri); “During the month I have been engaged in work at the office, getting out reports etc., which has kept me very closely confined.” (Duffin, 1904 Jan 30 Sat); “Have started the Elders at work getting the statistical and tithing reports tabulated preparatory to having them entered upon the report blanks, also purchased supply of account and other blank books for the year.” (Duffin, 1905 Jan 6 Fri); “During the week I have been working in the office, and having the book-keeper and recording secretary get data compiled for the making up of our reports for the year 1905.” (Duffin, 1906 Jan 6 Sat); “Have been working in the office during the month getting up the tithing and statistical reports &c. To-day 27th have completed them and got them ready to send to the Presiding Bishop” (Duffin, 1906 Jan 27 Sat).