The portion of present-day MD 33 between Easton and Saint Michaels was designated one of the original state roads when the Maryland State Roads Commission laid out the original state road system in 1909.
 However, the Easton–Saint Michaels road was not considered a necessary component of the system, so construction in its modern form was delayed in favor of the Easton–Wye Mills road.
 A 2-mile (3.2 km) section of the road between the eastern intersection with MD 329 and MD 370 was paved by 1910.
 The first sections of modern MD 33 constructed by the State Roads Commission were between Saint Michaels and Claiborne, which became the terminus of the Claiborne–Annapolis Ferry in 1919.
 Sections were completed between the two villages in 1919 and 1920.
 A section of the highway was also completed between Easton and the MD 370 intersection in 1920.
 The Easton–Claiborne Road was completed in 1924.
 When numbers were assigned to certain state highways beginning in 1927, the road was designated MD 17.

The next section of present-day MD 33 was constructed between Claiborne and the highway's present western terminus on Tilghman Island as MD 451.
 The sections from Claiborne to a point between Wittman and Sherman and on Tilghman Island were completed around 1930.
 The gap between Knapps Narrows and Sherman was filled in 1933.
 MD 451 was completed when a new single bascule drawbridge was completed over Knapps Narrows in 1934.
 MD 17 was extended from Claiborne across Eastern Bay along Romancoke Road to MD 404 in Matapeake on Kent Island in 1938.
 This section was added in response to the replacement of the Claiborne–Annapolis ferry route with a Claiborne–Romancoke route in 1938, with traffic following the new section of MD 17 to Matapeake to take a second ferry across the Chesapeake Bay to Annapolis.
 MD 17 switched numbers with MD 33, the highway connecting Brunswick and Wolfsville in Frederick County that is now MD 17 in 1940.

After a new, straighter US 213 (replaced by US 50 in 1949) was completed from south of Easton to Wye Mills in 1948, MD 33 was extended north along Washington Street within Easton to the new bypass.
 Following the closing of the Claiborne–Romancoke ferry in 1953, MD 33 and MD 451 switched alignments in 1957; MD 33 achieved its present western terminus at Tilghman Island while MD 451 became a short highway from MD 33 to Claiborne.
 MD 33 between Romancoke and Matapeake was redesignated MD 8 in 1960.
 MD 451 was removed from state maintenance in 1998.

Easton Parkway was constructed as a western bypass of Easton in the 1960s.
 MD 33 was moved from Washington Street to the part of the bypass north of present MD 33 when that section of Easton Parkway opened in 1965.
 MD 322, which was assigned to the southern part of Easton Parkway, replaced MD 33 on Bay Street between Easton Parkway and Washington Street, the latter of which became a northern extension of MD 565.
 In 1978, MD 322 was assigned to all of Easton Parkway and MD 33 assumed its present eastern terminus.
 The Knapps Narrows drawbridge was replaced by a new drawbridge in 1998.
 The 1934 drawbridge was transferred to the entrance of the Chesapeake Bay Maritime Museum in Saint Michaels.
The portion of present-day MD 33 between Easton and Saint Michaels was designated one of the original state roads when the Maryland State Roads Commission laid out the original state road system in 1909.  However, the Easton–Saint Michaels road was not considered a necessary component of the system, so construction in its modern form was delayed in favor of the Easton–Wye Mills road.  A 2-mile (3.2 km) section of the road between the eastern intersection with MD 329 and MD 370 was paved by 1910.  The first sections of modern MD 33 constructed by the State Roads Commission were between Saint Michaels and Claiborne, which became the terminus of the Claiborne–Annapolis Ferry in 1919.  Sections were completed between the two villages in 1919 and 1920.  A section of the highway was also completed between Easton and the MD 370 intersection in 1920.  The Easton–Claiborne Road was completed in 1924.  When numbers were assigned to certain state highways beginning in 1927, the road was designated MD 17.
The next section of present-day MD 33 was constructed between Claiborne and the highway's present western terminus on Tilghman Island as MD 451.  The sections from Claiborne to a point between Wittman and Sherman and on Tilghman Island were completed around 1930.  The gap between Knapps Narrows and Sherman was filled in 1933.  MD 451 was completed when a new single bascule drawbridge was completed over Knapps Narrows in 1934.  MD 17 was extended from Claiborne across Eastern Bay along Romancoke Road to MD 404 in Matapeake on Kent Island in 1938.  This section was added in response to the replacement of the Claiborne–Annapolis ferry route with a Claiborne–Romancoke route in 1938, with traffic following the new section of MD 17 to Matapeake to take a second ferry across the Chesapeake Bay to Annapolis.  MD 17 switched numbers with MD 33, the highway connecting Brunswick and Wolfsville in Frederick County that is now MD 17 in 1940.
After a new, straighter US 213 (replaced by US 50 in 1949) was completed from south of Easton to Wye Mills in 1948, MD 33 was extended north along Washington Street within Easton to the new bypass.  Following the closing of the Claiborne–Romancoke ferry in 1953, MD 33 and MD 451 switched alignments in 1957; MD 33 achieved its present western terminus at Tilghman Island while MD 451 became a short highway from MD 33 to Claiborne.  MD 33 between Romancoke and Matapeake was redesignated MD 8 in 1960.  MD 451 was removed from state maintenance in 1998.
Easton Parkway was constructed as a western bypass of Easton in the 1960s.  MD 33 was moved from Washington Street to the part of the bypass north of present MD 33 when that section of Easton Parkway opened in 1965.  MD 322, which was assigned to the southern part of Easton Parkway, replaced MD 33 on Bay Street between Easton Parkway and Washington Street, the latter of which became a northern extension of MD 565.  In 1978, MD 322 was assigned to all of Easton Parkway and MD 33 assumed its present eastern terminus.  The Knapps Narrows drawbridge was replaced by a new drawbridge in 1998.  The 1934 drawbridge was transferred to the entrance of the Chesapeake Bay Maritime Museum in Saint Michaels.
Maryland Route 33