Portage is in Columbia County, Wisconsin. The year each county in Wisconsin started specific record keeping is different. However, it was mandatory by state law by 1907 for all counties to do so and hence each record was then sent to the state office, as well. Eventhough those records for births and deaths came later than for marriages, the occurrence of a birth having been recorded may have been more for one being 'obligatory' rather than for one having done so for compulsory reasons. I have found this in the very early going - say even by the 1870s in neighboring Green Lake County. Do not overlook the fact that there may be a 'delayed birth record' for an individual. For example, this could be a record of birth filed during the 1940s for one born during the 1880s. Such a record can lead to interesting additional information by its reference to records used to support its reality. In one case for me it gave the church name where the baptismal record was recorded. James Heidel