The territory that is now Montgomery County was originally part of the Pottawattamie-Purchase in 1846 and was included in a large county called Pottawattamie in 1847. The General Assembly established the county on January 15, 1851. The county is named in honor of General Richard Montgomery who died at the assault of Quebec in the Revolutionary War.
The first county elections were held in April 1853, and around 18 votes were cast. Prior to this the county was attached to Adams County for judicial and financial reasons. These elections were held at the home of Amos G. Lowe, the first county judge.
A judge of the Sixth Judicial District appointed commissioners to select the county seat of Montgomery County. They selected a site nearest to the center of the county and named it Frankfort, in honor of Frankfort, Kentucky, the judge's hometown.
The first county courthouse was built in Frankfort in 1857. It was a simple wooden-frame structure that covered an area 20-foot x 40-foot and was built at a cost of $1,141.50 to the county. After a contest between Frankfort and Red Oak for the county seat, in which Frankfort lost by only six votes, this courthouse was moved. It was hitched to a team of oxen and towed to Red Oak in the winter of 1865. A blizzard came up, and the men had to abandon the building in favor of shelter. When they returned they had "lost" the courthouse in the snow. It was eventually found, but the "lost courthouse" was a great joke in Montgomery County for many years.
Even after a second story was added to the old courthouse, it was still not large enough for the growing county needs. Two attempts to build a new courthouse failed. The first one was in 1873, and the second was in 1883. Finally, on the third try, the people approved the building of a new courthouse by a narrow margin in the summer of 1889.
The second, and current, courthouse was built in 1890. The contractor failed to complete the building, and after much litigation, the county was found not responsible for the cost of completing the courthouse. When the building was finished, it only cost the county $69,000. At the dedication on the Fourth of July, conservative estimates put the number of visitors present at 10,000.
The nearly fireproof structure is made of sandstone and red brick. It is 91-foot x 72-foot and is 60 feet high, the clock tower extends another 40 feet. This clock tower was a gift of the Red Oak Monday Club. Since 1890 the courthouse has become the centerpiece of Red Oak and Montgomery County.
On July 2, 1981, the Montgomery County Courthouse was entered in the National Register of Historic Places. A brief ceremony and an open house were held.
1984 saw the completion of the elevator to assist the handicapped and elderly with access to all levels of the courthouse. The elevator reduced the double stairway leading to the second and third floors and the basement to a single stairway. The project also included a new entrance on the south side of the building.