Geography of Maryland
The U.S. state of Maryland has a varied geography. It has an area of 12,406.68 square miles (32,133.2 km2) and is comparable in overall area with Belgium [11,787 square miles (30,530 km2)].[1] It is the 42nd largest and 9th smallest state and is closest in size to the state of Hawaii (10,930.98 square miles (28,311.1 km2)), the next smallest state. The next largest state, its neighbor West Virginia, is almost twice the size of Maryland (24,229.76 square miles (62,754.8 km2)). Maryland borders Pennsylvania to the north, Delaware to the northeast, the Atlantic Ocean to the east, and to the west and south by West Virginia and Virginia.
Overview edit
Maryland possesses a variety of topography within its borders, contributing to its nickname America in Miniature. It ranges from sandy dunes dotted with seagrass in the east, to low marshlands teeming with wildlife and large bald cypress near the Chesapeake Bay, to gently rolling hills of oak forests in the Piedmont Region, and pine groves in the Maryland mountains to the west.
Maryland borders four states: it is bounded on its north by Pennsylvania, on its north and east by Delaware, on its east by the Atlantic Ocean, and on its south and west, across the Potomac River, by West Virginia and Virginia. The mid-portion of this latter border is interrupted by the District of Columbia, which sits on land that was originally part of Montgomery and Prince George's counties and including the town of Georgetown, Maryland. This land was ceded to the United States Federal Government in 1790 to form the District of Columbia. (The Commonwealth of Virginia gave land south of the Potomac, including the town of Alexandria, Virginia; however, Virginia retroceded its portion in 1846). The Chesapeake Bay nearly bisects the state and the counties east of the bay are known collectively as the Eastern Shore.
Most of the state's waterways are part of the Chesapeake Bay watershed, with the exceptions of a tiny portion of extreme western Garrett County (drained by the Youghiogheny River as part of the watershed of the Mississippi River), the eastern half of Worcester County (which drains into Maryland's Atlantic coastal bays), and a small portion of the state's northeast corner (which drains into the Delaware River watershed). So prominent is the Chesapeake in Maryland's geography and economic life that there has been periodic agitation to change the state's official nickname to the "Bay State", a nickname that has been used by Massachusetts for decades.
The highest point in Maryland, with an elevation of 3,360 feet (1,020 m), is Hoye Crest on Backbone Mountain, in the southwest corner of Garrett County, near the border with West Virginia, and near the headwaters of the North Branch of the Potomac River. Close to the small town of Hancock, in western Maryland, about two-thirds of the way across the state, less than 2 miles (3.2 km) separates its borders,[2] the Mason–Dixon line to the north, and the northwards-arching Potomac River to the south.
Portions of Maryland are included in various official and unofficial geographic regions. For example, the Delmarva Peninsula is composed of the Eastern Shore counties of Maryland, the entire state of Delaware, and the two counties that make up the Eastern Shore of Virginia, whereas the westernmost counties of Maryland are considered part of Appalachia. Much of the Baltimore–Washington corridor lies just south of the Piedmont in the Coastal Plain,[3] though it straddles the border between the two regions.
Geology edit
Earthquakes in Maryland are infrequent and small due to the state's distance from seismic/earthquake zones.[4][5] The M5.8 Virginia earthquake in 2011 was felt moderately throughout Maryland. Buildings in the state are not well-designed for earthquakes and can suffer damage easily.[6]
Maryland has no natural lakes, mostly due to the lack of glacial history in the area.[7] All lakes in the state today were constructed, mostly via dams.[8] Buckel's Bog is believed by geologists to have been a remnant of a former natural lake.[9]
Maryland has shale formations containing natural gas, where fracking is theoretically possible.[10]
Wildlife edit
Flora edit
As is typical of states on the East Coast, Maryland's plant life is abundant and healthy. A modest volume of annual precipitation helps to support many types of plants, including seagrass and various reeds at the smaller end of the spectrum to the gigantic Wye Oak, a huge example of white oak, the state tree, which can grow over 70 feet (21 m) tall.
Middle Atlantic coastal forests, typical of the southeastern Atlantic coastal plain, grow around Chesapeake Bay and on the Delmarva Peninsula. Moving west, a mixture of Northeastern coastal forests and Southeastern mixed forests cover the central part of the state. The Appalachian Mountains of western Maryland are home to Appalachian-Blue Ridge forests. These give way to Appalachian mixed mesophytic forests near the West Virginia border.[12]
Many foreign species are cultivated in the state, some as ornamentals, others as novelty species. Included among these are the crape myrtle, Italian cypress, southern magnolia, live oak in the warmer parts of the state,[13] and even hardy palm trees in the warmer central and eastern parts of the state.[14] USDA plant hardiness zones in the state range from Zones 5 and 6 in the extreme western part of the state to Zone 7 in the central part, and Zone 8 around the southern part of the coast, the bay area, and parts of metropolitan Baltimore.[15] Invasive plant species, such as kudzu, tree of heaven, multiflora rose, and Japanese stiltgrass, stifle growth of endemic plant life.[16] Maryland's state flower, the black-eyed susan, grows in abundance in wild flower groups throughout the state.
Fauna edit
The state harbors a considerable number of white-tailed deer, especially in the woody and mountainous west of the state, and overpopulation can become a problem. Mammals can be found ranging from the mountains in the west to the central areas and include black bears,[17] bobcats,[18] foxes, coyotes,[19] raccoons, and otters.[17]
There is a population of rare wild (feral) horses found on Assateague Island.[20] They are believed to be descended from horses who escaped from Spanish galleon shipwrecks.[20] Every year during the last week of July, they are captured and swim across a shallow bay for sale at Chincoteague, Virginia, a conservation technique which ensures the tiny island is not overrun by the horses.[20] The ponies and their sale were popularized by the children's book, Misty of Chincoteague.
The purebred Chesapeake Bay Retriever dog was bred specifically for water sports, hunting and search and rescue in the Chesapeake area.[21] In 1878, the Chesapeake Bay Retriever was the first individual retriever breed recognized by the American Kennel Club.[21] and was later adopted by the University of Maryland, Baltimore County as their mascot.
Maryland's reptile and amphibian population includes the diamondback terrapin turtle, which was adopted as the mascot of University of Maryland, College Park, as well as the threatened Eastern box turtle.[22] The state is part of the territory of the Baltimore oriole, which is the official state bird and mascot of the MLB team the Baltimore Orioles.[23] Aside from the oriole, 435 other species of birds have been reported from Maryland.[24]
The state insect is the Baltimore checkerspot butterfly, although it is not as common in Maryland as it is in the southern edge of its range.[25]
Environment edit
Maryland joined with neighboring states during the end of the 20th century to improve the health of the Chesapeake Bay. The bay's aquatic life and seafood industry have been threatened by development and by fertilizer and livestock waste entering the bay.[26][27]
In 2007, Forbes.com rated Maryland as the fifth "Greenest" state in the country, behind three of the Pacific States and Vermont. Maryland ranks 40th in total energy consumption nationwide, and it managed less toxic waste per capita than all but six states in 2005.[28] In April 2007, Maryland joined the Regional Greenhouse Gas Initiative (RGGI) — a regional initiative, formed by all the Northeastern states, Washington, D.C., and three Canadian provinces, to reduce greenhouse gas emissions.[29] In March 2017, Maryland became the first state with proven gas reserves to ban fracking by passing a law against it. Vermont has such a law, but no shale gas, and New York has such a ban, though it was made by executive order.[10]
Climate edit
Maryland has a wide array of climates, due to local variances in elevation, proximity to water, and protection from colder weather due to downslope winds.
The eastern half of Maryland — which includes the cities of Ocean City, Salisbury, Annapolis, and the southern and eastern suburbs of Washington, D.C., and Baltimore — lies on the Atlantic Coastal Plain, with flat topography and sandy or muddy soil. This region has a humid subtropical climate (Köppen Cfa), with hot, humid summers and a cool to cold winter; it falls under USDA Hardiness zone 8a.[15]
The Piedmont region — which includes northern and western greater Baltimore, Westminster, Gaithersburg, Frederick, and Hagerstown — has average seasonal snowfall totals generally exceeding 20 inches (51 cm), and, as part of USDA Hardiness zones 7b and 7a,[15] temperatures below 10 °F (−12 °C) are less rare. From the Cumberland Valley on westward, the climate begins to transition to a humid continental climate (Köppen Dfa).
In western Maryland, the higher elevations of Allegany and Garrett counties—including the cities of Cumberland, Frostburg, and Oakland—display more characteristics of the humid continental zone, due in part to elevation. They fall under USDA Hardiness zones 6b and below.[15]
Precipitation in the state is characteristic of the East Coast. Annual rainfall ranges from 35 to 45 inches (890 to 1,140 mm) with more in higher elevations. Nearly every part of Maryland receives 3.5–4.5 inches (89–114 mm) per month of rain. Average annual snowfall varies from 9 inches (23 cm) in the coastal areas to over 100 inches (250 cm) in the western mountains of the state.[30]
Because of its location near the Atlantic Coast, Maryland is somewhat vulnerable to tropical cyclones, although the Delmarva Peninsula and the outer banks of North Carolina provide a large buffer, such that strikes from major hurricanes (category 3 or above) occur infrequently. More often, Maryland gets the remnants of a tropical system that has already come ashore and released most of its energy. Maryland averages around 30–40 days of thunderstorms a year, and averages around six tornado strikes annually.[31]
Climate data edit
| City | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Oakland[32] | 34 °F (1 °C) 16 °F (−9 °C) | 38 °F (3 °C) 17 °F (−8 °C) | 48 °F (9 °C) 25 °F (−4 °C) | 59 °F (15 °C) 34 °F (1 °C) | 68 °F (20 °C) 45 °F (7 °C) | 75 °F (24 °C) 53 °F (12 °C) | 79 °F (26 °C) 58 °F (14 °C) | 78 °F (26 °C) 56 °F (13 °C) | 71 °F (22 °C) 49 °F (9 °C) | 62 °F (17 °C) 37 °F (3 °C) | 50 °F (10 °C) 28 °F (−2 °C) | 39 °F (4 °C) 21 °F (−6 °C) |
| Cumberland[33] | 41 °F (5 °C) 22 °F (−6 °C) | 46 °F (8 °C) 24 °F (−4 °C) | 56 °F (13 °C) 32 °F (0 °C) | 68 °F (20 °C) 41 °F (5 °C) | 77 °F (25 °C) 51 °F (11 °C) | 85 °F (29 °C) 60 °F (16 °C) | 89 °F (32 °C) 65 °F (18 °C) | 87 °F (31 °C) 63 °F (17 °C) | 80 °F (27 °C) 55 °F (13 °C) | 69 °F (21 °C) 43 °F (6 °C) | 57 °F (14 °C) 34 °F (1 °C) | 45 °F (7 °C) 26 °F (−3 °C) |
| Hagerstown[34] | 39 °F (4 °C) 22 °F (−6 °C) | 42 °F (6 °C) 23 °F (−5 °C) | 52 °F (11 °C) 30 °F (−1 °C) | 63 °F (17 °C) 39 °F (4 °C) | 72 °F (22 °C) 50 °F (10 °C) | 81 °F (27 °C) 59 °F (15 °C) | 85 °F (29 °C) 64 °F (18 °C) | 83 °F (28 °C) 62 °F (17 °C) | 76 °F (24 °C) 54 °F (12 °C) | 65 °F (18 °C) 43 °F (6 °C) | 54 °F (12 °C) 34 °F (1 °C) | 43 °F (6 °C) 26 °F (−3 °C) |
| Frederick[35] | 42 °F (6 °C) 26 °F (−3 °C) | 47 °F (8 °C) 28 °F (−2 °C) | 56 °F (13 °C) 35 °F (2 °C) | 68 °F (20 °C) 45 °F (7 °C) | 77 °F (25 °C) 54 °F (12 °C) | 85 °F (29 °C) 63 °F (17 °C) | 89 °F (32 °C) 68 °F (20 °C) | 87 °F (31 °C) 66 °F (19 °C) | 80 °F (27 °C) 59 °F (15 °C) | 68 °F (20 °C) 47 °F (8 °C) | 56 °F (13 °C) 38 °F (3 °C) | 45 °F (7 °C) 30 °F (−1 °C) |
| Baltimore[36] | 42 °F (6 °C) 29 °F (−2 °C) | 46 °F (8 °C) 31 °F (−1 °C) | 54 °F (12 °C) 39 °F (4 °C) | 65 °F (18 °C) 48 °F (9 °C) | 75 °F (24 °C) 57 °F (14 °C) | 85 °F (29 °C) 67 °F (19 °C) | 90 °F (32 °C) 72 °F (22 °C) | 87 °F (31 °C) 71 °F (22 °C) | 80 °F (27 °C) 64 °F (18 °C) | 68 °F (20 °C) 52 °F (11 °C) | 58 °F (14 °C) 43 °F (6 °C) | 46 °F (8 °C) 33 °F (1 °C) |
| Elkton[37] | 42 °F (6 °C) 24 °F (−4 °C) | 46 °F (8 °C) 26 °F (−3 °C) | 55 °F (13 °C) 32 °F (0 °C) | 67 °F (19 °C) 42 °F (6 °C) | 76 °F (24 °C) 51 °F (11 °C) | 85 °F (29 °C) 61 °F (16 °C) | 88 °F (31 °C) 66 °F (19 °C) | 87 °F (31 °C) 65 °F (18 °C) | 80 °F (27 °C) 57 °F (14 °C) | 69 °F (21 °C) 45 °F (7 °C) | 58 °F (14 °C) 36 °F (2 °C) | 46 °F (8 °C) 28 °F (−2 °C) |
| Ocean City[38] | 45 °F (7 °C) 28 °F (−2 °C) | 46 °F (8 °C) 29 °F (−2 °C) | 53 °F (12 °C) 35 °F (2 °C) | 61 °F (16 °C) 44 °F (7 °C) | 70 °F (21 °C) 53 °F (12 °C) | 79 °F (26 °C) 63 °F (17 °C) | 84 °F (29 °C) 68 °F (20 °C) | 82 °F (28 °C) 67 °F (19 °C) | 77 °F (25 °C) 60 °F (16 °C) | 68 °F (20 °C) 51 °F (11 °C) | 58 °F (14 °C) 39 °F (4 °C) | 49 °F (9 °C) 32 °F (0 °C) |
| Waldorf[39] | 44 °F (7 °C) 26 °F (−3 °C) | 49 °F (9 °C) 28 °F (−2 °C) | 58 °F (14 °C) 35 °F (2 °C) | 68 °F (20 °C) 43 °F (6 °C) | 75 °F (24 °C) 53 °F (12 °C) | 81 °F (27 °C) 62 °F (17 °C) | 85 °F (29 °C) 67 °F (19 °C) | 83 °F (28 °C) 65 °F (18 °C) | 78 °F (26 °C) 59 °F (15 °C) | 68 °F (20 °C) 47 °F (8 °C) | 59 °F (15 °C) 38 °F (3 °C) | 48 °F (9 °C) 30 °F (−1 °C) |
| Point Lookout State Park[40] | 47 °F (8 °C) 29 °F (−2 °C) | 51 °F (11 °C) 31 °F (−1 °C) | 60 °F (16 °C) 38 °F (3 °C) | 70 °F (21 °C) 46 °F (8 °C) | 78 °F (26 °C) 55 °F (13 °C) | 86 °F (30 °C) 64 °F (18 °C) | 89 °F (32 °C) 69 °F (21 °C) | 87 °F (31 °C) 67 °F (19 °C) | 81 °F (27 °C) 60 °F (16 °C) | 71 °F (22 °C) 49 °F (9 °C) | 61 °F (16 °C) 41 °F (5 °C) | 50 °F (10 °C) 32 °F (0 °C) |
| [41] | ||||||||||||
| Climate data for Baltimore (Baltimore/Washington International Airport) (1991−2020 normals, extremes 1872–present) | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| Record high °F (°C) | 79 (26) | 83 (28) | 90 (32) | 94 (34) | 98 (37) | 105 (41) | 107 (42) | 105 (41) | 101 (38) | 98 (37) | 86 (30) | 77 (25) | 107 (42) |
| Mean daily maximum °F (°C) | 43.2 (6.2) | 46.4 (8.0) | 54.8 (12.7) | 66.5 (19.2) | 75.5 (24.2) | 84.4 (29.1) | 88.8 (31.6) | 86.5 (30.3) | 79.7 (26.5) | 68.3 (20.2) | 57.3 (14.1) | 47.5 (8.6) | 66.6 (19.2) |
| Daily mean °F (°C) | 34.3 (1.3) | 36.6 (2.6) | 44.3 (6.8) | 55.0 (12.8) | 64.4 (18.0) | 73.5 (23.1) | 78.3 (25.7) | 76.2 (24.6) | 69.2 (20.7) | 57.4 (14.1) | 46.9 (8.3) | 38.6 (3.7) | 56.2 (13.4) |
| Mean daily minimum °F (°C) | 25.4 (−3.7) | 26.9 (−2.8) | 33.9 (1.1) | 43.6 (6.4) | 53.3 (11.8) | 62.6 (17.0) | 67.7 (19.8) | 65.8 (18.8) | 58.8 (14.9) | 46.5 (8.1) | 36.5 (2.5) | 29.6 (−1.3) | 45.9 (7.7) |
| Record low °F (°C) | −7 (−22) | −7 (−22) | 4 (−16) | 15 (−9) | 32 (0) | 40 (4) | 50 (10) | 45 (7) | 35 (2) | 25 (−4) | 12 (−11) | −3 (−19) | −7 (−22) |
| Average precipitation inches (mm) | 3.08 (78) | 2.90 (74) | 4.01 (102) | 3.39 (86) | 3.85 (98) | 3.98 (101) | 4.48 (114) | 4.09 (104) | 4.44 (113) | 3.94 (100) | 3.13 (80) | 3.71 (94) | 45.00 (1,143) |
| Average snowfall inches (cm) | 6.4 (16) | 7.5 (19) | 2.8 (7.1) | 0.0 (0.0) | 0.0 (0.0) | 0.0 (0.0) | 0.0 (0.0) | 0.0 (0.0) | 0.0 (0.0) | 0.0 (0.0) | 0.1 (0.25) | 2.5 (6.4) | 19.3 (49) |
| Average precipitation days (≥ 0.01 in) | 10.1 | 9.3 | 11.0 | 11.2 | 11.9 | 11.3 | 10.4 | 9.6 | 9.1 | 8.6 | 8.5 | 10.3 | 121.3 |
| Average snowy days (≥ 0.1 in) | 2.8 | 2.9 | 1.5 | 0.1 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.2 | 1.5 | 9.0 |
| Average relative humidity (%) | 63.2 | 61.3 | 59.2 | 58.9 | 66.1 | 68.4 | 69.1 | 71.1 | 71.3 | 69.5 | 66.5 | 65.5 | 65.8 |
| Mean monthly sunshine hours | 155.4 | 164.0 | 215.0 | 230.7 | 254.5 | 277.3 | 290.1 | 264.4 | 221.8 | 205.5 | 158.5 | 144.5 | 2,581.7 |
| Percent possible sunshine | 51 | 54 | 58 | 58 | 57 | 62 | 64 | 62 | 59 | 59 | 52 | 49 | 58 |
| Source: NOAA[42][verification needed][43][44] | |||||||||||||
| Sea temperature data for Baltimore | |||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Year |
| Average sea temperature °F (°C) | 46.0 (7.8) | 44.4 (6.9) | 45.1 (7.3) | 50.4 (10.2) | 55.9 (13.3) | 68.2 (20.1) | 75.6 (24.2) | 77.4 (25.2) | 73.4 (23.0) | 66.0 (18.9) | 57.2 (14.0) | 50.7 (10.4) | 59.2 (15.1) |
| Mean daily daylight hours | 10.0 | 11.0 | 12.0 | 13.0 | 14.0 | 15.0 | 15.0 | 14.0 | 12.0 | 11.0 | 10.0 | 9.0 | 12.2 |
| Source: Weather Atlas[45] | |||||||||||||
See also edit
References edit
- ^ "Belgium". CIA World Factbook. Central Intelligence Agency. May 15, 2008. Retrieved May 15, 2008.
Area—comparative: about the size of Maryland
- ^ "Hancock—C&O Canal Trust". Chesapeake and Ohio Canal Trust.
- ^ Delgado, Patricia (December 2011). "Chesapeake Bay National Estuarine Research Reserve in Maryland Site Profile" (PDF). Maryland Department of Natural Resources. p. 54. Retrieved May 21, 2017.
Map showing ... Maryland physiographic provinces
- ^ . Archived from the original on January 17, 2013. Retrieved November 25, 2012.
- ^ . Archived from the original on November 2, 2012. Retrieved November 25, 2012.
- ^ Reger, James P. "Earthquakes and Maryland". Maryland Geological Survey. Retrieved December 25, 2018.
- ^ . Maryland Geological Survey. January 24, 2007. Archived from the original on May 29, 2010. Retrieved February 3, 2008.
- ^ Maryland.gov, "Maryland at a glance". Accessed December 3, 2018.
- ^ Rosenwald, Michael S. (July 30, 2012). "Fact: Maryland has no natural lakes". The Washington Post. Retrieved June 10, 2015.
- ^ a b Pamela Wood (March 27, 2017). "Maryland General Assembly approves fracking ban". The Baltimore Sun.
- ^ "Maryland at a Glance: State Symbols, Maryland State Flower—Black-Eyed Susan". Maryland Manual Online. Maryland State Archives. Retrieved May 20, 2014.
- ^ Olson, D. M.; Dinerstein, E.; et al. (2001). "Terrestrial Ecoregions of the World: A New Map of Life on Earth". BioScience. 51 (11): 933–938. doi:10.1641/0006-3568(2001)051[0933:TEOTWA]2.0.CO;2.
- ^ "Zone Hardiness Map through Prairie Frontier". Prairiefrontier.com. Retrieved October 24, 2010.
- ^ John Leeds Bozman (1837). The history of Maryland: from its first settlement, in 1633, to the restoration, in 1660; with a copious introduction, and notes and illustrations. J. Lucas & E.K. Deaver. p. 24.
- ^ a b c d "Hardiness Zones". Arbor Day Foundation. Retrieved March 5, 2013.
- ^ "Invasive Species of concern in Maryland". Mdinvasivesp.org. Retrieved October 24, 2010.
- ^ a b . Archived from the original on August 30, 2007. Retrieved August 30, 2007.
- ^ Therres, Glenn (Fall 2007). (PDF). Wildlife and Heritage. Maryland Department of Natural Resources. Archived from the original (PDF) on April 19, 2011. Retrieved July 6, 2009.
Historically bobcats were distributed statewide but during the post colonization period densities began to plummet. By the mid-1900s, populations had probably reached all-time lows, with remnant populations existing only in western Maryland. This prompted the Department of Natural Resources (DNR) to classify them as a state-listed "Species of Special Concern." During the past quarter century, occupied range and densities have increased markedly. Results from the annual Bowhunter Survey and the Hunter Mail survey have identified bobcat sightings in 14 of Maryland's 23 counties. Currently, bobcats have dual legal classification in Maryland. In addition to the Species of Special Concern designation, they are also defined as a Game Animal / Furbearer with a closed harvest season.
- ^ . Maryland Department of Natural Resources. Archived from the original on August 15, 2011. Retrieved September 16, 2011.
Coyotes were historically a western species with core populations found west of the Mississippi River. Alterations and/or elimination of competing predators during the post-European colonization period facilitated rapid range expansion into eastern North America during the 20th Century. Established populations now occur in every state and province in North America. Coyotes are a relatively new addition to local ecosystems, and were first documented in Maryland during 1972. Initial substantiated sightings occurred in Cecil, Frederick and Washington counties. Since that time population densities and occupied range have expanded incrementally and coyotes now occur statewide.
- ^ a b c "Assateague Island National Seashore wild Ponies". Assateagueisland.com. Retrieved October 24, 2010.
- ^ a b . K9web.com. Archived from the original on October 24, 2010. Retrieved October 24, 2010.
- ^ . Maryland Biodiversity Project. Archived from the original on July 9, 2018. Retrieved July 8, 2018.
- ^ "Maryland Government Website—Maryland State Bird". Msa.md.gov. June 7, 2010. Retrieved October 24, 2010.
- ^ (PDF). Maryland/District of Columbia Records Committee. Archived from the original (PDF) on July 9, 2018. Retrieved May 4, 2009.
- ^ Euphydryas phaeton (Drury, 1773) September 6, 2010, at the Wayback Machine, Butterflies and Moths of North America
- ^ Goodman, Peter S. (August 1, 1999). "An Unsavory Byproduct: Runoff and Pollution". Washington Post. p. A1.
- ^ Horton, Tom (January 1, 1999). . Baltimore Sun. Archived from the original on October 12, 2013. Retrieved October 5, 2013.
- ^ Wingfield, Brian; Marcus, Miriam (October 16, 2007). . Forbes.com. Archived from the original on November 5, 2010. Retrieved October 24, 2010.
- ^ "Program Design Archive". RGGI, Inc. Retrieved April 20, 2018.
- ^ . Archived from the original on May 22, 2010. Retrieved October 24, 2010.
- ^ . Archived from the original on October 16, 2011. Retrieved October 25, 2006.
- ^ "Monthly Averages for Oakland, MD". weather.com. Retrieved September 28, 2013.
- ^ "Station Name: MD Cumberland 2". National Oceanic and Atmospheric Administration. Retrieved March 5, 2013.
- ^ "Monthly Averages for Hagerstown, MD". weather.com. Retrieved September 28, 2013.
- ^ "Station Name: MD Frederick Police Brks". National Oceanic and Atmospheric Administration. Retrieved March 5, 2013.
- ^ "Station Name: MD MD Sci Ctr Baltimore". National Oceanic and Atmospheric Administration. Retrieved February 27, 2013.
- ^ "Monthly Averages for Elkton, MD (21921)". The Weather Channel. Retrieved May 21, 2017.
- ^ "Station Name: MD Ocean City Muni Ap". National Oceanic and Atmospheric Administration. Retrieved March 5, 2013.
- ^ "Monthly Averages for Waldorf, MD". The Weather Channel. Retrieved May 21, 2017.
- ^ "Monthly Averages for Point Lookout State Park [Scotland, MD]". The Weather Channel. Retrieved May 21, 2017.
- ^ "NowData—NOAA Online Weather Data". National Oceanic and Atmospheric Administration. Retrieved December 17, 2012.
- ^ "NowData – NOAA Online Weather Data". National Oceanic and Atmospheric Administration. Retrieved May 24, 2021.
- ^ "Station: Baltimore Wash INTL AP, MD". U.S. Climate Normals 2020: U.S. Monthly Climate Normals (1991–2020). National Oceanic and Atmospheric Administration. Retrieved May 24, 2021.
- ^ "WMO Climate Normals for BALTIMORE/BALTO-WASH, MD 1961–1990". National Oceanic and Atmospheric Administration. Retrieved May 24, 2021.
- ^ "Baltimore, Maryland, USA – Monthly weather forecast and Climate data". Weather Atlas. Retrieved January 24, 2019.