Midland Tunnel No. 3 (Chaffee County, Colorado)
Built 1887 by the Colorado Midland Railroad
Third of four tunnels on CR 371 north of Buena Vista
Open to one-lane traffic

Midland Tunnel No. 4 (Chaffee County, Colorado)
Built 1887 by the Colorado Midland Railroad
Fourth of four tunnels on CR 371 north of Buena Vista
Open to one-lane traffic

Milk River Bridge (Blaine County, Montana)
Built 1916
Timber through truss bridge over Milk River on CR 178
Open to traffic

Mill Creek Bridge (Washington County, Missouri)
Built 1935
Concrete tee beam bridge over Mill Creek on Route M
Open to traffic

Mill Creek Bridge (Bourbon County, Kansas)
Built 1927
Through arch bridge over Mill Creek on North Crawford in Fort Scott
Open to traffic

Mill Creek Bridge (Crawford County, Indiana)
Built 1885; rehabilitated 2000
Through truss bridge over Mill Creek on CR 220 East
Open to traffic

Mill Creek Bridge (Wasco County, Oregon)
Built 1948
Deck truss bridge over Mill Creek on US 26
Open to traffic

Mill Creek Bridge (Wabaunsee County, Kansas)
Built ca. 1935
Through truss bridge over Mill Creek on Willard Road, 1.0 mi. east and 0.2 mi. north of Maple Hill
Open to traffic

Mill Creek Bridge (Wabaunsee County, Kansas)
Deck plate girder bridge over Mill Creek on Southern Pacific Railroad
Open to traffic

Mill Creek Bridge (Wasco County, Oregon)
Built 1920; rehabilitated 2001
Stringer bridge over Mill Creek on W 6th Street in City of the Dalles
Open to traffic

Mill Creek Covered Bridge (Parke County, Indiana)
Built 1907 by D.M. Brown
Covered bridge over Mill Creek on CR N550W
Open to traffic

Mill Creek MO 47 (Washington County, Missouri)
Built 1964
Steel stringer bridge over Mill Creek on Mo 47 S
Open to traffic

Mill Creek Park Suspension Bridge (Mahoning County, Ohio)
Built 1895 by the Youngstown Bridge Co.
Suspension bridge over Mill Creek in Mill Creek Park at Youngstown
Open to traffic

Mill Creek Swinging Bridge (Miller County, Missouri)
Built by Joseph Dice; rehabilitated 1978
Swinging bridge over Mill Creek on Lake Road 42-18 (Swinging Bridges Road) near Brumley
Open to one-lane traffic

Mill Road Bridge (Darke County, Ohio)
Built 1881 by the Massillon Bridge Co.
Through truss bridge over Greenville Creek on TR 385 in Gettysburg
Open to traffic

Mill Street Bridge (Columbia County, Wisconsin)
Pony/through plate girder bridge over Union Pacific Railroad on Mill Street in Lodi
Open to traffic

Millard Crossing Bridge (Logan County, Arkansas)
This bridge crosses Shoal Creek on north east side of Magazine mountain at the former town of Millard
Timber stringer bridge over Shoal Creek on Forest Service road #1601
Open to traffic

Miller Creek Bridge (Alexander County, Illinois)
Built 1933
Pony truss bridge over Miller Creek on Old Illinois Route 3 northeast of Thebes, 1 mi. north of Thebes
Open to two-lane traffic

Miller Creek Bridge (Independence County, Arkansas)
Built 1914 by Hartford & Fugatt of Batesville
Two-span arch bridge over Miller Creek on Miller Creek Road (CR 86) in Batesville
Open to one-lane traffic

Miller Creek Stone Bridge (Wayne County, Missouri)
Built ca. 1930
Low-water bridge with stone masonry foundations on CR 417 over Miller Creek beyond the end of Route JJ
Open to traffic with a 4 ton weight limit

Millers Bridge (Butler County, Missouri)
Built 1924
Pony truss bridge over Cane Creek on Route PP (Old US 60) west of Poplar Bluff
Open to two-lane traffic

Millersville Bridge (Cape Girardeau County, Missouri)
Built 1923; rehabilitated 1975
Two-span through truss bridge over Whitewater River on MO 72 at Millersville
Open to two-lane traffic on a paved road

Million Dollar Bridge (Valdez-Cordova Census Area, Alaska)
Built 1910 on the CR&NW Railroad; closed 1938; reopened as a highway bridge in 1958; fourth span collapsed in earthquake on March 27, 1964, collapsed span repaired 2005
Four-span through truss bridge over Copper River on Copper River Highway
Open to one-lane traffic

Milltown High Street Bridge (Warren County, Pennsylvania)
Built 1937; rehabilitated 1982
Pony truss bridge over Tionesta Creek on PA 2002 (High Street) in Milltown
Open to traffic

Milwaukee River Broadway St. Bridge (Milwaukee County, Wisconsin)
Built 1982
Bascule bridge over Milwaukee River on Broadway Street (WI 32) in Milwaukee
Open to traffic

Milwaukee River Parkway, Lincoln Park, North Branch (Milwaukee County, Wisconsin)
Built 1940
Bridge over North Branch Milwaukee River on Milwaukee River Parkway
Open to traffic

Milwaukee River Parkway, Lincoln Park, South Branch (Milwaukee County, Wisconsin)
Built 1940
Bridge over South Branch Milwaukee River on Milwaukee River Parkway
Open to traffic

Milwaukee Road Railroad Overpass (Missoula County, Montana)
Built 1936
Lost tee beam bridge over the abandoned Milwaukee Road Railroad on Orange Street in Missoula
Open to traffic

Milwaukee Street Bridge (Rock County, Wisconsin)
Built 1913
Concrete arch bridge over Rock River on Milwaukee Street in Janesville
Open to traffic

Mine Creek Bridge (Linn County, Kansas)
Built 1914
Concrete arch bridge over Mine Creek, 8.8 mi. north and 3.4 mi. east of Prescott
Open to traffic

Mine Creek Bridge (Linn County, Kansas)
Built 1927
Rainbow arch bridge over Mine Creek on Ungeheuer Road (Old US 69), five miles north of Prescott
Open to traffic

Miner Street Bridge (Clear Creek County, Colorado)
Built 1902 by Kuyes and Work. Reconstructed 1990 (the trusses are no longer load-bearing).
Reconstructed pony truss bridge over Clear Creek on Miner Street in Idaho Springs
Open to traffic

Minerva Creek Bridge (Marshall County, Iowa)
Built 1912
Arch bridge over Minerva Creek on a local road
Open to traffic

Minerva Creek Bridge (Marshall County, Iowa)
Built 1919
Pony truss bridge over Minerva Creek on a local road
Open to traffic

Mingo Ditch Bridge (Stoddard County, Missouri)
Formerly a bridge on the Frisco Hoxie Branch railroad built in 1926 (?) and refurbished for vehicle use when the line was discontinued
Pony truss bridge over Mingo Ditch southwest of Puxico on CR 499
Open to one-lane traffic on a gravel road with a 17 ton weight limit

Mingo Ditch Route T Bridge (Stoddard County, Missouri)
Built 1955
Steel stringer bridge with wooden piers over Mingo Ditch on Route T
Open to two-lane traffic

Minneapolis Railroad Bridge (Ottawa County, Kansas)
Through truss bridge over Pipe Creek on the Kyle Railroad at Minneapolis
Open to traffic

Minnesota River Bridge (Blue Earth County, Minnesota)
Built 1954
Through truss bridge over Minnesota River on CR 42
Open to traffic

Minnow Creek Bridge (Johnson County, Arkansas)
Built 1942 by the Works Progress Administration
Tee beam bridge over Minnow Creek on CR 50
Open to traffic

Minnow Slough Bridge (Crawford County, Illinois)
Built 1909
Steel stringer bridge over Minnow Slough on TR 163, 1 mi. east of Palestine
Open to traffic

Minnow Slough Bridge No. 2 (Crawford County, Illinois)
Built 1909; rehabilitated 1982
Steel stringer bridge over Minnow Slough on TR 169A, 1.5 mi. NE Palestine
Open to traffic

Minot Viaduct (Ward County, North Dakota)
Massive steel railroad trestle over the Coteau di Missouri Valley on the BNSF Railroad, west of Minot
Still in use

Mirror Lake Bridge No. 1 (Stone County, Arkansas)
Built 1935 by the CCC
Stone arch bridge over Blanchard Springs Drainage on FR 1110
Open to traffic

Mirror Lake Bridge No. 2 (Stone County, Arkansas)
Built 1935 by the CCC
Stone arch bridge over Blanchard Springs Drainage on FR 1110
Open to traffic

Mission Bridge over the Los Angeles River (Los Angeles County, California)
Built 1944; rehabilitated 1955
Concrete arch bridge over Los Angeles River on US 101 in Los Angeles
Open to traffic

Mississinewa River IN 1 Bridge (Randolph County, Indiana)
Built 1941; rehabilitated 1979 and 2008
Through truss bridge over Mississinewa River on IN 1
Open to traffic

Mississippi County Road 307 Bridge (Mississippi County, Missouri)
Built 1921
Pony truss on CR 307 (Old US 60) near Birds Point over a drainage ditch emptying into Brewer Lake in Wyatt
Open to traffic on a paved road with a 20 ton weight limit

Mississippi County Road 310 Bridge (Mississippi County, Missouri)
Built ca. 1922; relocated here 1966
Pony truss bridge over a drainage ditch on CR 310
Open to traffic

Mississippi County Road 314 Bridge (Mississippi County, Missouri)
Built 1922 as part of a bridge with at least two spans; relocated here in 1965
Pony truss bridge over Ditch 29 on CR 314, just off MO 77 south of Wyatt
Open to traffic

Mississippi County Road 319 Bridge (Mississippi County, Missouri)
Built 1922 as part of a bridge with at least two spans; relocated here 1965
Pony truss bridge over Ditch 29 on CR 319 just off MO 77
Open to traffic

Mississippi County Road 322 Bridge (Mississippi County, Missouri)
Built ca. 1922; relocated here 1966
Pony truss bridge over Spillway Ditch on CR 322 southeast of Charleston
Open to traffic on a gravel road

Mississippi County Road 325 Bridge (Mississippi County, Missouri)
Built 1922; relocated here in 1966
Pony truss bridge over Spillway Ditch on CR 325 southeast of Charleston
Open to traffic on a gravel road

Mississippi County Road 418 Bridge (Mississippi County, Missouri)
Built ca. 1922; relocated here 1970
Pony truss bridge over St. James Ditch on CR 418 west of MO 105
Open to traffic

Mississippi County Road 521 Bridge (Mississippi County, Missouri)
Built ca. 1922; relocated here 1965
Pony truss bridge on CR 521 over Wilkinson Drainage Ditch just west of MO 102
Open to traffic

Mississippi River Bridge (Grant County, Wisconsin)
Built 1982
Steel through arch bridge over Mississippi River on US 61/US 151
Open to traffic

Mississippi River I-40 Bridge (Shelby County, Tennessee)
Built 1973
Two-span steel through arch bridge over the Mississippi River on I-40 at Memphis
Open to traffic

Mississippi River US 61 Bridge (Dubuque County, Iowa)
Built 1982
Steel through arch bridge over the Mississippi River on US 61 and US 151
Open to traffic

Missouri Street Bridge (Washington County, Missouri)
Pony truss bridge over Breton Creek on Missouri Street in Potosi, just south of the courthouse
Open to traffic

Mistaken Creek Bridge (Grayson County, Kentucky)
Built ca. 1920
Bedstead pony truss bridge over Mistaken Creek on Yeaman-Olaton Road
Open to traffic

Mobridge Railroad Bridge (Walworth County, South Dakota)
Through truss bridge over Missouri River (Oahe Lake) on the BNSF Railroad between Mobridge and Wakpala
Open to traffic

Modrow Road Bridge (Cowlitz County, Washington)
Built 1958
Steel arch bridge over Kalama River on Modrow Road
Open to traffic

Moline Main Street Bridge (Elk County, Kansas)
Pony truss on North Main Street over Wildcat Creek in Moline
Open to one lane traffic on a paved street

Mollys Run Bridge (Jefferson County, Indiana)
Built 1905
Pony truss bridge over Mollys Run on Brooksburg Manville Road (CR 260N)
Open to one-lane traffic

Monett Business US 60 Bridge (Barry County, Missouri)
Built 1935
Through truss bridge over the railroad on Business US 60 east of Monett
Open to two-lane traffic

Moniteau Church Road Bridge (Moniteau County, Missouri)
Built ca. 1930
Pony truss bridge over Howard Creek on Moniteau Church Road southwest of Jamestown
Open to traffic

Moniteau Creek Road Bridge (Cole County, Missouri)
Built 1915; made obsolete by a new bridge on MO 179 in 1967
Through truss bridge over Moniteau Creek on Moniteau Creek Road (Old MO 179)
Open to traffic

Monroe Street Bridge (Monroe County, Michigan)
Built 1927; Subsequent work 1970 & 1984; rehabilitated 1990
Concrete cantilever bridge over Raisin River on M-125 in Monroe
Open to traffic

Monroe Street Bridge (Cook County, Illinois)
Built 1919
Bascule bridge over South Branch Chicago River on W. Monroe Street in Chicago
Open to traffic

Montezuma Bridge (Parke County, Indiana)
Built 1949; rehabilitated 1987
Six-span through truss bridge over Wabash River on US 36 at Montezuma
Open to two-lane traffic

Montoursville Bridge (Lycoming County, Pennsylvania)
Built 1931; rehabilitated 1994
Three-span through truss bridge over Loyalsock Creek on PA 2014 in Montoursville
Open to traffic

Monument Road Bridge (Harris County, Georgia)
Built 1930
Truss bridge over Sand Creek on Monument Road
Open to traffic

Mopac Railroad Bridge (Shelby County, Illinois)
Built 1896
Girder bridge over Tr 222 on Mopac Rr (Union Pacific)
Open to traffic

Morgan Oak Street Arch Bridge (Cape Girardeau County, Missouri)
Small concrete arch bridge on Morgan Oak Street over a ditch formerly occupied by the Missouri Pacific Railroad
Open to traffic on a city street

Morman Fork CR 81 Bridge (Bates County, Missouri)
Pony truss bridge over a branch of Morman Fork on CR 81 (West Boone Road)
Open to traffic

Morrison Bluff Bridge (Logan County, Arkansas)
At 1.6 miles this is the longest bridge in Arkansas
Bridge over Arkansas River on AR 109 at Morrison Bluff
Open to traffic

Morrison Creek Bridge (Sullivan County, Indiana)
Built 1935
Pony truss bridge over Morrison Creek on CR 75 North
Open to traffic

Morrison Street Bridge (Multnomah County, Oregon)
Built 1958
Bascule bridge over Willamette River on Morrison Street in Portland
Open to traffic

Morton Bridge (Ray County, Missouri)
Built by the Wrought Iron Bridge Co.
Through truss bridge over Crooked River on Landing Road
Open to traffic

Mosby Creek Covered Bridge (Lane County, Oregon)
Built in 1920. Oldest covered bridge in Lane County. Restored in 1990.
Howe through truss bridge on Mosby Creek Road
Open to traffic

Mosier Creek Bridge (Wasco County, Oregon)
Built 1920
Concrete arch bridge over Mosier Creek on HWY 100 in Mosier
Open to traffic

Moss Road Bridge (Blount County, Alabama)
Built 1940
Through truss bridge over Calvert Prong Little War on Moss Road
Open to traffic

Mossy Creek Route 613 Bridge (Augusta County, Virginia)
Built 1910
Pony truss bridge over Mossy Creek on Route 613
Open to traffic

Mott Bridge (Douglas County, Oregon)
Built 1936
Wooden arch bridge over North Umpqua River on a local road
Open to traffic

Mound Road Bridge (Shelby County, Indiana)
Through truss bridge over Flatrock River on Mound Road
Open to traffic

Moundsville WV 2 Spur Over Ohio River (Marshall County, West Virginia)
Built 1986
Steel through arch bridge over Thmpsn Av;Lckwd Av;Ohior on Wv 2 Spur
Open to traffic

Mount Carmel Bridge (Wabash County, Illinois)
Built 1932; rehabilitated 1987
Through truss bridge over Wabash River on IL 15/IN 64 in Mount Carmel
Open to traffic

Mount Hope Bridge (Bristol County, Rhode Island)
Built 1929; rehabilitated 1985
Suspension bridge over Mount Hope Bay on RI 114 in Bristol
Open to traffic

Mount Pleasant Covered Bridge (Perry County, Pennsylvania)
Built 1918
Covered bridge over Shermans Creek on Mount Pleasant Road (TR 304)
Open to traffic

Mountain Fork Bridge (Polk County, Arkansas)
Built 1905
Two-span pony truss bridge over Mountain Fork Creek on CR 38 near the community of Camp Pioneer
Open to traffic

Mountain Fork River Bridge (McCurtain County, Oklahoma)
Built 1948
Through truss bridge over Mountain Fork River on US 70
Open to traffic

Mountain Glen Bridge (Union County, Illinois)
Pony truss bridge over a branch of Clear Creek near Mountain Glen
Open to traffic on a paved road

Mountain St. over the Verdugo Wash (Los Angeles County, California)
1936
Pony truss bridge over Verdugo Wash on Mountain St. in Glendale, Los Angeles County, California
Open to Traffic

Mozart Road Trestle (Jefferson County, Illinois)
Timber stringer bridge over Trib to Rayse Creek on CSX Railroad (formerly L&N Railroad), alongside Mozart Road about 3 miles west of Woodlawn
Open to railroad traffic

Mud Creek Bridge (Marion County, Kansas)
Concrete pony arch bridge over Mud Creek, 0.6 mi. north of Marion
Open to traffic

Muddy Creek Bridge (Butler County, Kansas)
Built 1910
Two-span concrete arch bridge over Muddy Creek, 3.2 mi. east and 1.0 mi. north of Douglass
Open to traffic

Muddy Creek Old US 65 Bridge (Pettis County, Missouri)
Built ca. 1930
Through truss bridge over Muddy Creek on Claycomb Road (Old US 65) north of Sedalia
Open to traffic

Mulberry Relief Creek Bridge (Franklin County, Arkansas)
Built 1940
Steel stringer bridge over Mulberry Relief Creek on CR 67 - D
Open to traffic

Mulberry River AR 23 Bridge (Franklin County, Arkansas)
Built 1935 by McEachin and McEachin, Inc., of Little Rock
Three-span pony truss bridge over Mulberry River on AR 23
Open to traffic

Mulberry River US 64 Bridge (Crawford County, Arkansas)
Built 1929; rehabilitated 1961
Three-span open-spandrel arch bridge over Big Mulberry River on US 64 in Mulberry
Open to traffic

Mulholland Drive over the Hollywood Freeway (Los Angeles County, California)
Built 1940
Concrete tee beam bridge over Hollywood Freeway (US 101) on Mulholland Drive in Los Angeles
Open to traffic