State Trunk Highway 145 (STH-145, commonly known as Highway 145 or WIS 145) is a 24.7-mile (39.8 km) state highway in Milwaukee, Waukesha, and Washington counties in Wisconsin, United States, that connects the northwest suburbs of Milwaukee with the city's downtown. For much of its route, the highway is known as Fond du Lac Avenue.

Up until the fall of 2009, WIS 145's northern terminus was at the freeway interchange with US Highway 41 (US 41) in Richfield. A project involving the construction of five roundabouts in a less than one mile span has truncated the highway's northern terminus to the freeway interchange with US-45, with the stretch of roundabouts between US-41 and US-45 now designated as County Trunk Highway FD (CTH-FD). WIS 145 travels generally southeast through Germantown as a secondary highway. Upon reaching Menomonee Falls, the road expands into a four-lane boulevard for just over one mile (1.6 km), straddling the Waukesha–Milwaukee county line before intersecting with US 41/US 45 again.

At this point, the road heads into the city limits of Milwaukee and becomes a freeway, officially known as the Fond du Lac Freeway, though this term is rarely used locally. Although it was originally planned to continue into the heart of downtown, the freeway ends after just under five miles (8.0 km) at which point it intersects with 68th Street and Hampton Avenue. WIS 145 continues as Fond du Lac Avenue into downtown. It is a four-lane boulevard until Burleigh Street, at which point it becomes a four-lane urban arterial. It becomes a four-lane boulevard again at 20th Street until its intersection with Sixth Street. A major interchange at Interstate 43 (I-43) is just past the intersection with Walnut Street. WIS 145 turns south onto Sixth Street before terminating at the intersection with US 18 (Wells Street), adjacent to the Wisconsin Center.

WIS 145 was once also a part of the Park East Freeway, a short spur running east from its intersection with I-43, over the Milwaukee River before terminating at Broadway and Milwaukee Street at East Knapp Street. The freeway was demolished between 2002 and 2003, with the replacement surface streets not complete until 2006.

Originally, the freeway portion of WIS 145 was to extend further southeast and there was to be a major interchange located near the intersection of W. Lisbon Road and W. North Avenue, connecting the Fond du Lac with the proposed extension of the Stadium Freeway and the proposed Bay Freeway. This was never built.

In October 1975, Milwaukee County Executive John Doyne proposed connecting this freeway with the Stadium North stub end, existing four miles (6.4 km) to the south. While this gap closure has not been built to date due to public opposition, the current state trunk highway map shows a freeway planned for this corridor.

County	Location	mi	km	Exit	Destinations	Notes
Milwaukee	Milwaukee	0.0	0.0		US 18	Southern terminus
		0.9	1.4		I-43	Exit 72A on I-43
		1.6	2.6		WIS 57 south (N. 17th Street)	Southeastern end of WIS 57 concurrency
		1.8	2.9		WIS 57 north (N. 20th Street)	Northwestern end of WIS 57 concurrency
		4.7	7.6		WIS 190 (W. Capitol Drive)
		6.3	10.1		Fond du Lac Avenue	Southeastern end of freeway
		6.7	10.8	7A	Grantosa Avenue, Villard Avenue	Southbound exit and northbound entrance only
		7.0	11.3	7B	WIS 181 (76th Street)
		7.4	11.9	8	Silver Spring Drive	Northbound exit to eastbound only; southbound exit to westbound only
		8.4	13.5	9	91st Street
		9.2	14.8	10A	Green Tree Road, 102nd Street	Southbound entrance and northbound exit only
		9.7	15.6	10B	107th Street, Good Hope Road, Fond du Lac Ave	Signed for Good Hope Road northbound only; signed for Fond du Lac Avenue southbound only
		10	16	10C	Park Place
		11.3	18.2		I-41 / US 45 / WIS 100	Exit 47B on US 41/US 45/WIS 100
Waukesha	Menomonee Falls	12.7	20.4		WIS 100 (Main Street)
Washington	Village of Germantown	16.5	26.6		WIS 167 east (Mequon Road)	Eastern end of WIS 167 concurrency
		16.8	27.0		WIS 167 west (Mequon Road)	Western end of WIS 167 concurrency
	Richfield	23.2	37.3		US 45	Exit 60 on US 45
		23.7	38.1		I-41 / US 41	Exit 60 on US 41
		24.7	39.8		WIS 175	Northern terminus
1.000 mi = 1.609 km; 1.000 km = 0.621 mi       Concurrency terminus       Incomplete access

• U.S. Roads portal

• WIS 145 Terminus Photos
• Wisconsin Highways: Milwaukee Freeways: Fond du Lac Freeway, Christopher Bessert