Missionaries sent a report to mission administrators every week. In theory, conference secretaries mailed instructions to each companionship Thursday evenings, which the Elders retrieved Mondays when they sent their weekly reports.  Below are photos of the report books of Elder Calvin H Chandler, who served in the Southwestern States Mission from 1899 to 1901. 
All images were created with permission from and posted here courtesy of the L Tom Perry Special Collections, Harold B Lee Library, Brigham Young University, Provo, UT 84602.
The books are about 6? x 6? and are made of relatively thin paper held together by three metal staples.  There seems to have been a cover made of differently colored paper.
The header says:
INDIAN TERRITORY MISSION ____ Conference City or Town ____ / ELDER?S REPORT / Month ____ / 189___ Addressed to } Pres. ____ / or } Sec ____ / Report No. ___ Elders Names }____ / ____ / Standing Address } ____ / ____ Recorded in ___ Date of Month ___ / Book
The title is ?Elder?s Report?; I don?t know if the Sisters used the same or a different report. The ?City or Town? changed almost every week and was sometimes ?on road.? The ?Standing Address? was usually given as a city, county, and state; the Elders collected mail at the post office of that city rather than receiving it at a specific residence. It only changed when the missionary was assigned to a different county.
The ?President? could be the Mission or the Conference President and Chandler?s reports alternate between them (almost) every week; the addressee is a secretary only rarely.  The ?Report No.? is a week number, 1-52, with ?1? being the first week in January. I don?t know what ?Recorded in ___ Date of Month ___ / Book? indicates.
The header says ?Indian Territory Mission,? which was the name of the mission before 1898 when it was changed to the ?Southwestern States Mission.? Beginning in 1900 Chandler crossed out the ?189__? and wrote in the year. He did not cross out the mission name. 
The body of the report consists of a list of categories with blank columns for each day of the week, Monday through Sunday, and a weekly total. Above the name of each day is a space for the date. The categories are:
Miles Walked, Miles Otherwise Traveled Families Visited, Families Revisited, Gospel Conversations, Adults Present, Refused Entertainment Tracts Distributed, Books Sold ____ Kind and Amount, Books Given Away ____ do Books Loaned Meetings Held Attendance, No. Adults to whom Testimony borne, Refused Opportunities of Meetings, Rejected Testimonies of Elders, Baptisms, Children Blessed, Sick Administered to
I don?t know what the rules were for assigning any of these numbers.  I?m assuming: ?Miles Otherwise Traveled? means by train, boat, car, cart, etc; ?do? = ?ditto?; ?No.? = ?number?; ?Children Blessed? means ?children given a name and a blessing? and not just children administered to for health or comfort. For the ?Books? categories, Chandler used abbreviations like ?VW? for A Voice of Warning. Some weeks a category like ?Books Loaned? or ?Baptisms? is left blank in Chandler?s record book, presumably because there were no instances that week, but all the categories have at least occasional data.
At the bottom of the report was a space for ?REMARKS: —Condition of Health, Etc.,? and a place for the ?Elder?s Name.? Chandler?s remarks tended to be brief: ?good health,? etc.
Each page folded out a perforated, detachable duplicate. Presumably the missionaries filled out both forms and then sent the one on the right to the Conference leadership, leaving both the Elder and the mission administration with a complete record. As in the example below, however, sometimes the duplicate was not filled in.
As a missionary progressed through the year, the report books got thinner. In the photo below, all of the duplicates have been removed from the top book. The bottom book has about two-thirds of the duplicates in place. 
The missionaries also used the back of reports, as shown below.  Most of the reports seem, to my untrained eye, to have been written with a black-leaded pencil, but a few of the pages have blue writing.
You can see the remnants of the perforations on the left edge of the photo.
One of my first thoughts upon handling the report books was, ?there is no way a booklet like this would have survived two years with me.? Although there are tears and discoloration, I think the books are remarkably well preserved for being carried around for two years without a hardback cover. I wonder how Elder Chandler kept the books from damage.
More generally, I think the report books fit into the broader transitions of the Church and American society in the late Nineteenth and early Twentieth Centuries. A mass-produced, pre-printed report book for quantitative data with a systematic report schedule is an artifact of a bureaucratic institution. 
The ?Southwestern States Mission? series uses the diaries of
six seven eight (as of 2012 Jun 17) missionaries who served in eastern Texas or, in the case of the Sister missionaries, in Kansas and Missouri, around 1900 to illustrate aspects of Mormon material culture, lived religion, and social History. The missionaries are Mission President Duffin, Elders Brooks, Clark, Folkman, Forsha, and Jones, and Sisters Carling and Cluff. The series is inspired by Ardis Parshall?s serial posting of the missionary diary of Willard Larson Jones at Keepapitchinin. Previous installment here.
 I don?t know at what point the mail/report schedule developed or how long it lasted. It seems to have been in effect throughout the period of this study (1899-1906). In practice, the secretaries were sometimes late and the missionaries trekked to the Post Office more often than just once per week. I hope to deal with mail and trips to the Post Office more specifically in a later post. There are fifty-three diary entries that unambiguously indicate the mailing of reports; thirty-seven were on Monday and ten on Tuesday. ??after dinner we packed up our grip, all ready for our journey, the next day, as we were going to Tyler Co. we also made out our reports ready to mail as we went by the post office.? (Brooks, 1901 Mar 10 Sun); ??after dinner I passed the time in writing and Making out my weekly reports? (Forsha, 1900 Jun 11 Mon); ?we go in Emblem and Send our reports to headquarters and mail Some letters? (Clark, 1900 Nov 05 Mon); ?We had not yet mailed our reports so we thought we had better go to the post office? (Jones, 1901 Feb 12 Tue). From a letter sent to all missionaries in the Central States Mission, dated 1904 Apr 11: ?It seems there has been some mis-understanding about mail day, in consequence of which Elders have been going to their post-office two or three times a week, thus losing much valuable time and causing a great deal of unnecessary walking to be done. The conference secretaries have been instructed to send out all mail Thursday evening which will give it time to reach you by the regular report and mail day – Monday.? (Duffin, 1904 Apr 11 Mon).
I have not examined mission-level records, but the South Texas Conference record book for this time period is at the Church History Library. It contains lists of baptisms and hand-drawn tables containing the names of each missionary and their weekly totals for each (most? I only looked briefly) of the categories in the report, followed by a conference total.
 The BYU catalog and the Church History Library Catalog identify the booklets as ?report books.? I find one example in the diaries: ?I sent my report book home.? (Jones, 1901 Apr 01 Mon). Calvin Harris Chandler [1877-1940], ?Calvin Harris Chandler missionary journals, 1899-1901,? MSS 3314, L Tom Perry Special Collections, Harold B Lee Library, Brigham Young University. The file/box also contains Chandler?s mission journals, a typescript of the journals, and photographs. There are multiple report books at the Church History Library and elsewhere, but Chandler?s is the only one I?ve examined; I don?t know how representative it is.
 By ?thin? I?m guessing ?less than 20 lb,? but not like onion-skin or tissue paper.
 Of the 72 reports in the first book (1899 May 14 to 1900 Sep 30), 37 are addressed to the mission president, 32 to a conference president, 2 to a secretary, and 1 with no addressee (or so faint that I can?t read it).
 The mission name was changed again to ?Central States Mission? in 1904. Two weeks before the end of his mission Chandler was transferred to Missouri. In his report for the last full week he wrote in ?Northern States? above ?Indian Territory.?
 That is, for example, I don?t know if there was a certain length of time one had to converse before one could count a ?Gospel Conversation.?
 I?d guess a new book was 3/8? to 1/2? thick while a completed book was about 1/4? thick. There are seventy-two reports in the completed booklet, so, with duplicates, a new booklet had about 150 pages. I don’t know if 72 was the original length or if some pages were torn out.
 Chandler did not write on the back every week, but on multiple occasions he wrote baptismal information, child blessings, what sound like journal entries, and, occasionally, arithmetic calculations of his weekly totals. I don?t know if he wrote on the backs of the reports he submitted.
 Without making a specific claim, I think Thomas Alexander?s Mormonism in Transition and Robert Wiebe?s The Search for Order 1877-1920 have something to say about mass-produced report books (as would, I?m sure, other books written less than twenty-five years ago). It is a cliché that ?what gets measured gets managed.? Some of the categories on the report show up in the diaries as stock phrases. I imagine that there were other consequences to systematizing the reporting system.