The first state highway to this location was WI-152, which was built in 1923 starting at WI-35 in Danbury and heading west to the river. Highway WI-77 was built west in the late 1940s, reaching Danbury in 1951. At that time, the designation WI-152 was removed from the Danbury to state line section, which became part of WI-77.
On the Minnesota side, MN-48 was authorized in 1933 and built during the great depression. It was paved in the early 1950s.
The 1914 wagon bridge was certainly replaced at one time, likely in the late 1930s or just after WWII, likely with a truss bridge of some type. If anyone knows for sure, please let me know. This replacement bridge would have been obsolete by the 1970s, leading to it being replaced in 1984. The 1984 bridge is a very modern and very functional prestressed concrete girder bridge. With reasonable maintenance, it should last 100 years. The bridge is, however, completely devoid of any decorations, it was built purely for cost and function. That is too bad given the spectacular setting and the importance of the Saint Croix River.
The WI-77 highway in this area was once proposed to be part of a major highway, US-402. That highway would have been a diagonal route running from Sioux Falls, SD, to near Sault Ste Marie in Ontario. That route was never built. MN-23 serves part of the function, but even today, diagonal travel in western Minnesota is slow going.
The photo above is a view of the river crossing as seen from traffic level traveling eastbound from Minnesota heading towards Wisconsin.