on the north side of fort wayne at the dupont road interchange of interstate 69 (i-69), the northern section of sr 1 begins and heads east. the road heads away from i–69 as a six-lane divided highway, along the south edge of the parkview regional medical center complex, passing through numerous commercial properties. the highway narrows to a four-lane divided highway at diebold road and then enters an area of mixed commercial and residential properties. at tonkel road, sr 1 begins to curve northeast toward leo and narrows to a two-lane highway. the route then leaves fort wayne, passing through rural farm land with scattered houses. curving due north to enter leo on main street, sr 1 then passes through residential areas of that town. north of downtown leo the highway curves northeast and passes through a mix of commercial and residential properties. as the road enters dekalb county it curves to run due north. the highway then enters spencerville, passing through the center of town. after spencerville, the road curves northeast, before again turning back north. the highway enters st. joe and takes a sharp curve to head due east. the route crosses csx railroad tracks and makes another sharp curve heading due north. the road continues north until it meets sr 8. the two routes head east-southeast for a concurrency, until sr 1 departs the joint section heading due north. the road then passes through rural farmland, with a few houses, as a two-lane highway. upon entering butler it crosses the norfolk southern railroad tracks, before encountering a signalized intersection with us 6 in downtown butler. sr 1 then leaves butler heading due north until it intersects dekalb county road 46, at which point the highway turns northwest. the route enter hamilton and begins a concurrency with sr 427, heading northeast and passing hamilton lake. after , sr 1 leaves the concurrency heading due north. the highway then continues in that direction until reaching its northern terminus at us 20.