Interstate 465 (I-465), also known as the USS Indianapolis Memorial Highway, is the beltway circling Indianapolis, Indiana, United States. It is roughly rectangular in shape and has a perimeter of approximately . It lies almost completely within the boundaries of Marion County, except for two short sections on the north leg in Boone and Hamilton counties. It intersects with I-65, I-69, I-70, and I-74 and provides additional access to I-65 via I-865.
Route description
All U.S. and state highways that formerly were routed through the central part of Indianapolis are now routed concurrently with I-465. Only I-65 and I-70 run through Downtown Indianapolis. The affected highways are:
I-74, running counterclockwise from exit 16 to exit 49
US 31, running counterclockwise from exit 2 to exit 31
US 36, running counterclockwise from exit 13 to exit 42
US 40, running counterclockwise from exit 12 to exit 46
US 52, running clockwise from exit 25 to exit 47
US 421, running counterclockwise from exit 49 to exit 27
SR 37, running counterclockwise from exit 4 to exit 37
SR 67, running counterclockwise from exit 8 to exit 42
In addition, , the I-69 extension will run counterclockwise from future exit 5 to exit 37. When the interchange opens, it is expected the SR 37 designation will be removed from I-465 and replaced by I-69.
An approximately section between exits 46 and 47 carries eight routes: I-465, US 31, US 36, US 40, US 52, US 421, SR 37, and SR 67, tying a short segment of Georgia State Route 10 Loop in Athens, Georgia for the largest concurrency in the U.S. In most cases, route markers other than I-74's are not posted along I-465 itself; rather, signs on the entrance ramps direct traffic traveling a particular route to follow I-465 to a specific exit to continue on that route.
History
Planning and alignment selection
A beltway for Indianapolis was part of the original plan of the Interstate Highway System in 1955. The general alignment was to be either on or adjacent to the now-defunct SR 100, which, by then, had only two completed legs—on the north side, along 86th Street west of the White River and 82nd Street east of the river, and on the east side, along Shadeland Avenue. On the city's west side, an alignment corridor paralleling High School Road was preferred, and, on the south side, one between Hanna Avenue and Thompson Road had been proposed. Development along 86th Street made its use unfeasible for I-465, so a 91st Street alignment was initially proposed. This proved to be controversial and caused many delays in final alignment selection for the north leg, postponing its construction by several years.
Initial construction (1959–1970) The I-465 beltway was constructed in segments. There were 16 segments along the original proposed semicircumferential alignment between I-65 in Boone County at exit 129 and that same highway to the south at exit 123 in Marion County. Indiana highway officials recognized the value of having the route be a full circumferential, so using non-Interstate federal funding and employing a temporary designation of SR 100, they planned a separate 17th segment northward between I-65 at its exit 123 and the north leg of I-465 in Boone County. By the time that added section was completed in 1970, Indiana had obtained federal approval to sign it as I-465 as well, resulting in the creation of a dogleg section of I-465 outside of the loop (now signed as I-865).
State highway officials concentrated on building the west and south legs of I-465 early in the overall project, since they were the missing portions of the SR 100 concept. Construction began in 1959, and the first section of the I-465 beltway to be completed was the portion on the west leg between I-65 near Eagle Creek Park and I-74/US 136 in Speedway. That section was opened to traffic on September 26, 1961, simultaneously with the adjacent section of I-65 northwest from there running to 71st Street. By July 18, 1962, all four segments of the original west leg were open between SR 67 (Kentucky Avenue) and I-65, but the interchange with I-70 in that stretch was not completed until much later that decade when the segment of that route from I-465 west to SR 43 opened in 1968.