A revised environmental impact study to account for the butterfly's habitat in the northern area of the freeway was approved in 2004. The study compared the original routing for this extension that involved connecting directly to I-196 at I-94 with an alternate route that involved an indirect connection via the BL I-94 interchange and an I-94 concurrency near Benton Harbor. The study recommended using a version of the alternate connection to avoid the Blue Creek Fen, both to save money and decrease impact to the Mitchell's satyr. At the time the freeway segment opened in 2003, MDOT expected the remaining segment would not take much longer to complete, but since then, funding has not been available. MDOT did not include construction of the extension for this reason in the department's 2014–18 highway projects plan released in 2013, although most of the design work and land acquisition has been completed. Until the missing freeway segment is built, US 31 follows a stretch of Napier Avenue, which was upgraded in conjunction with the St. Joseph Valley Parkway opening to that point, westward to I-94. The US 31/I-94/BL I-94 interchange will be converted to a cloverleaf interchange and additional lanes will be added to I-94 as well. The St. Joseph Valley Parkway name has already been applied to this unbuilt section. MDOT's 2017–21 plan draft released in July 2016 split the remaining work into three phases. The department has listed funding for only the first two of these three phases, and construction is anticipated to start in 2021.