New York State Route 198 (NY 198) is a state highway located entirely within the city of Buffalo, New York, in the United States. It is named the Scajaquada Expressway for Scajaquada Creek, which it parallels as it heads across northern Buffalo. NY 198 connects the Niagara Thruway (Interstate 190 or I-190) in the Black Rock neighborhood to the Kensington Expressway (NY 33) on Buffalo's east side. On average, the highway carries over 37,000 cars per day.

NY 198 begins at exit 11, a trumpet interchange, of I-190 in the Black Rock section in the city of Buffalo, alongside the Niagara River. NY 198 proceeds northeastward as the Scajaquada Expressway, a four-lane expressway through Buffalo. Just after the interchange, the route crosses over NY 266 (Niagara Street) and westbound serves an interchange with NY 266 and NY 265. NY 198 winds northeast into the West Side of Buffalo, crossing the campus of Buffalo State College as it enters an interchange with Grant Street, accessible from both directions. At this interchange, NY 198 bends eastward along the northern edge of campus, passing the football field, Moore Dining Hall, and several halls as it bends southeast alongside the campus.

Now in the Elmwood section of Buffalo, NY 198 bends eastward once again, entering the interchange with County Route 119 (CR 119; Elmwood Avenue). After the interchange, NY 198 bends northeast, with a ramp from the college merging in. Running alongside Park Lake, NY 198 enters the North Buffalo section of the city. The four-lane expressway crosses through Delaware Park, crossing the tennis courts and into an interchange with NY 384 (Delaware Avenue). After NY 384, NY 198 bends southeast, passing north of Forest Lawn Cemetery and south of Delaware Park Golf Course. After entering an at-grade intersection with Parkside Avenue, NY 198 leaves Delaware Park and returns to a four-lane limited-access expressway.

After the conversion, NY 198 interchanges with NY 5 (Main Street) just north of the Humboldt-Hospital station of Buffalo's Metro Rail. The expressway crosses under Kensington Avenue and continues southeast past the Main-Humboldt Townhouses. Entering the Masten section of Buffalo, NY 198 continues southeast into an interchange with NY 33 (the Kensington Expressway), where the Scajaquada Expressway merges into the Kensington. This merge marks the eastern terminus of the NY 198 designation.

The modern NY 198 corridor was originally served by Scajaquada Drive and Humboldt Parkway, two surface streets that linked Delaware Park to Humboldt Park (now Martin Luther King, Jr. Park). Scajaquada Drive began at Grant Street and went eastward through Delaware Park to Agassiz Circle. Here, it met Humboldt Parkway, which ran from NY 384 in Delaware Park to Fillmore Avenue at Humboldt Park by way of the modern Scajaquada and Kensington Expressway corridors. Construction of the Scajaquada Expressway began in the early 1960s. The first section of the freeway extended from Grant Street to NY 384 and was completed by 1961. An extension west to the Niagara Thruway opened in 1962, at which time all of the expressway was designated as NY 198. The portion of Humboldt Parkway between NY 384 and the Kensington Expressway was upgraded into a divided highway in the mid-1960s, at which time it became part of NY 198.

Community activists have proposed that the highway be downgraded to a pedestrian-friendly roadway more in harmony with the surrounding communities. The New York State Department of Transportation is investigating the feasibility of the project, currently estimated to cost around $85 million. According to the state, no work will be performed until 2016 at the earliest.

The entire route is in Buffalo, Erie County. All exits are unnumbered.